Practice Test

Q1) A particle moving in a magnetic field increases its velocity then its radius of the circle Show Answer

Q2) Two charged particles are projected into a region in which a magnetic field is perpendicular to their velocities. After they enter the magnetic field, you can conclude that Show Answer

Q3) A charge is fired through a magnetic field. The force acting on the charge is maximum when the angle between the direction of motion of charge and the magnetic field is Show Answer

Q4) The field due to a long straight wire carrying a current I is proportional to Show Answer

Q5) The forces existing between two parallel current carrying conductors is F. If the current in each conductor is doubled, then the value of force will be Show Answer

Q6) The force between two parallel current carrying wires is independent of Show Answer

Q7) An electron and a proton have equal kinetic energies. They enter in a magnetic field perpendicular to B, then Show Answer

Q8) The ratio of magnetism potentials due to magnetic dipole in the end on position to that in broad side on position for the same distance from it is Show Answer

Q9) A long copper tube of inner radius R carries a current i. The magnetic field B inside the tube is Show Answer

Q10) A wire of length l is bent into a circular loop of radius R and carries a current I. The magnetic field at the centre of the loop is B. The same wire is now bent into a double loop of equal radii. If both loop carry the same current I and it is in the same direction, the magnetic field at the centre of the double loop will be Show Answer

Q11) Gauss is unit of which quantity Show Answer

Q12) A bar magnet is cut into two equal halves by a plane parallel to the magnetic axis. Of the following physical quantities, the one which remains unchanged is Show Answer

Q13) An electric current passes through a long straight copper wire. At a distance 5 cm from the straight wire, the magnetic field is B. The magnetic field at 20 cm from the straight wire would be Show Answer

Q14) The areas of cross-section of three magnets of same length area A,2 A and 6A respectively. The ratio of their magnetic moments will be Show Answer

Q15) A proton a mass m and charge +e is moving in a circular orbit in a magnetic field with energy 1 MeV. What should be the energy of α-particle (mass =4m and charge =+2e), so that it can revolve in the path of same radius Show Answer

Q16) The magnetic field at the point of intersection of diagonals of a square loop of side L carrying a current I is Show Answer

Q17) A current i is passing through a straight conductor of infinite length. The magnetic field at a point situated at a distance R from the conductor is Show Answer

Q18) A current of 1 ampere is passed through a straight wire of length 2.0 metres. The magnetic field at a point in air at a distance of 3 metres from either end of wire and lying on the axis of wire will be Show Answer

Q19) An electron and proton having same kinetic energy enter into magnetic field perpendicular to it. Then Show Answer

Q20) An alternating electric field, of frequency v, is applied across the dees (radius =R) of a cyclotron that is being used to accelerated protons (mass =m). The operating magnetic field (B) used in the cyclotron and the kinetic energy (K) of the proton beam, produced by it, are given by Show Answer

Q21) A steady electric current is flowing through a cylindrical conductor Show Answer

Q22) A beam of protons is moving parallel to a beam of electrons. Both the beams will tend to Show Answer

Q23) A wire of length l metre carrying a current i ampere is bent in the form of a coil having two turns. Its magnitude of magnetic moment will be Show Answer

Q24) A length of wire carries a steady current. It is bent first to form a circular coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is Show Answer

Q25) A particle of mass m and charge q moves with a constant velocity v along the positive x direction. It enters a region containing a uniform magnetic field B directed along the negative z direction, extending from x=a to x=b. The minimum value of v required so that the particle can just enter the region x>b is Show Answer

Q26) Two very long, straight, parallel wires carry steady current i and-i resepectively. The distance between the wires is d. At a certain instant of time, a point charge q is at a point equidistant from the two wires, in the plane of the wires. Its instantaneous magnitude of the force due to the magnetic field acting on the charge at this instant is Show Answer

Q27) The magnetic field due to a straight conductor of uniform cross section of radius a and carrying a steady current is represented by Show Answer

Q28) The magnetic field at the point of intersection of diagonals of a square wire loop of side L carrying a current I is Show Answer

Q29) Magnetic dipole moment of a rectangular loop is Show Answer

Q30) A cylindrical conductor of radius ‘R’ carries a current ‘i’. The value of magnetic field at a point which is R/4 distance inside from the surface is 10T. Find the value of magnetic field at point which is 4R distance outside from the surface Show Answer

Q31) The magnetic dipole moment of a current loop is independent of Show Answer

Q32) Two circular coils are made of two identical wires of same length. If the number of turns of two coils are 4 and 2, then the ratio of magnetic induction at centres will be zero Show Answer

Q33) Magnetic field at the centre of a circular coil of radius Rdue to i flowing through it is B. The magnetic field at a point along the axis at distance R from the centre is Show Answer

Q34) A straight conductor carrying current I.If the magnetic field at a distance r is 0.4T, then magnetic field at a distance 2r will be Show Answer

Q35) Which of the field pattern given in the figure is valid for electric field as well as for magnetic field? Show Answer

Q36) A current carrying coil is subjected to a uniform magnetic field. The coil will orient so that its plane becomes Show Answer

Q37) An electron is projected along the axis of a circular conductor carrying some current. Electron will experience force Show Answer

Q38) If the current is doubled, the deflection is also doubled in Show Answer

Q39) A charge moves in a circle perpendicular to a magnetic field. The time period of revolution is independent of Show Answer

Q40) A stream of electrons is projected horizontally to the right. A straight conductor carrying a current is supported parallel to electron stream and above it. If the current in the conductor is from left to right, then what will be the effect on electron stream? Show Answer

Q41) A circular coil A of radius r carries current i. Another circular coil B of radius 2r carries current of i. The magnetic fields at the centres of the circular coils are in the ratio of Show Answer

Q42) A charge q is moving in a magnetic field then the magnetic force does not depend upon Show Answer

Q43) A current carrying circular loop is freely suspended by a long thread. The plane of the loop will point in the direction Show Answer

Q44) A current is flowing through a thin cylindrical shell of radius R. If energy density in the medium, due to magnetic field, at a distance r from axis of the shell is equal to U then which of the following graphs is correct Show Answer

Q45) An electron of charge e moves with a constant speed v along a circle of radius r. Its magnetic moment will be Show Answer

Q46) Uniform magnetic B is directed vertically upwards and 3 wires of equal length L, carrying equal current i are lying in a horizontal plane such that the first one is along north, second one along north-east and the third one at 60° north of east. Force exerted by magnetic field B on them is Show Answer

Q47) There are 50 turns of a wire in every cm length of a long solenoid. If 4 ampere current is flowing in the solenoid, the approximate value of magnetic field along its axis at an internal point and at one end will be respectively Show Answer

Q48) A current of 5 ampere is flowing in a wire of length 1.5 metres. A force of 7.5 N acts on it when it is placed in a uniform magnetic field of 2 tesla. The angle between the magnetic field and the direction of the current is Show Answer

Q49) Two parallel wires carrying currents in the same direction attract each other because of Show Answer

Q50) A proton (or charged particle) moving with velocity v is acted upon by electric field E and magnetic field B. The proton will move undeflected if Show Answer

Q51) A neutral point is obtained at the centre of a vertical circular coil carrying current. The angle between the plane of the coil and the magnetic meridian is Show Answer

Q52) The deflection in a galvanometer falls from 50 division to 20 when a 12 Ω shunt is applied. The galvanometer resistance is Show Answer

Q53) A length l of wire carries a steady current i. It is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give three loops of smaller radius. The magnetic field at the centre caused by the same current is Show Answer

Q54) A long thin hollow metallic cylinder of radius ‘R’ has a current i ampere. The magnetic induction ‘B’-away from the axis at a distance r from the axis varies as shown in Show Answer

Q55) A circular coil of radius R carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a distance r from the centre of the coil, such that r>>R, varies as Show Answer

Q56) A wire of length L is bent in the form of a circular coil and current i is passed through it. If this coil is placed in a magnetic field then the torque acting on the coil will be maximum when the number of turns is Show Answer

Q57) A charge moving with velocity v in X-direction is subjected to a field of magnetic induction in the negative X-direction. As a result, the charge will Show Answer

Q58) Two parallel beams of protons and electrons, carrying equal currents are fixed at a separation d. The protons and electrons move in opposite directions. P is a point on a line joining the beams, at a distance x from any one beam. The magnetic field at P is B. If B is plotted against x, which of the following best represents the resulting curve Show Answer

Q59) Positively charged particles are projected into a magnetic field. If the direction of the magnetic field is along the direction of motion of the charge particles, the particles get Show Answer

Q60) The deflection in moving coil galvanometer is reduced to half, when it is shunted with a 40 Ω coil. The resistance of the galvanometer is Show Answer

Q61) In a cyclotron, the angular frequency of a charged particle is independent of Show Answer

Q62) A solenoid of 1.5 m length and 4.0 cm diameter has 10 turns per cm. A current of 5 A is flowing through it. The magnetic field induction at axis inside the solenoid is Show Answer

Q63) If a copper rod carries a direct current, the magnetic field associated with the current will be Show Answer

Q64) The coil of a moving coil galvanometer is wound over a metal frame in order to Show Answer

Q65) An electron and a proton are projected at right angles to a uniform magnetic field with the same kinetic energy. Then Show Answer

Q66) An electron and a proton with equal momentum enter perpendicularly into a uniform magnetic field, then Show Answer

Q67) A circular coil is in y-z plane with centre at origin. The coil is carrying a constant current. Assuming direction of magnetic field at x=-25 cm to be positive direction of magnetic field, which of the following graphs shows variation of magnetic field along x-axis Show Answer

Q68) The helium nucleus makes a full rotation in a circle of radius 0.8 m in 2 s. The value of the magnetic field induction B in tesla at the centre of circle will be Show Answer

Q69) The unit of electric current “ampere” is the current which when flowing through each of two parallel wires spaced 1 m apart in vacuum and of infinite length will give rise to a force between them equal to Show Answer

Q70) An electron rotates about a proton, the induced magnetic field is 14T at the centre, find out the angular velocity of electron if radius of rotation is 0.5 nm Show Answer

Q71) The electrons in the beam of television tube move horizontally form south to north. The vertical component of the earth’s magnetic field points down. The electron is deflected towards Show Answer

Q72) An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has a magnitude of Show Answer

Q73) The magnetic field at the centre of a current carrying circular loop is B. If the radius of the loop is doubled, keeping the current same, the magnetic field at the centre of the loop would be Show Answer

Q74) A current i flows along the length of an infinitely long, straight, thin-walled pipe. Then Show Answer

Q75) The magnetic field lines due to a bar magnet are correctly shown in Show Answer

Q76) A proton (mass m and charge +e) and an α-particle (mass 4m and charge +2e) are projected with the same kinetic energy at right angles to the uniform magnetic field. Which one of the following statements will be true Show Answer

Q77) Two particles A and B having equal charges +6C, after being accelerated through the same potential difference, enter a region of uniform magnetic field and describe circular paths of radii 2cm and 3cm respectively. The ratio of mass of A to that of B is Show Answer

Q78) A current I flow in an infinitely long wire cross-section in the form of a semi-circular ring of radius R. The magnitude of the magnetic induction along its axis is Show Answer

Q79) An electron is revolving around a proton in a circular path of diameter 0.1 nm. It produces a magnetic field
14 T at a proton. Then the angular speed of the electron is Show Answer

Q80) 1A current flows through an infinitely long straight wire. The magnetic field produced at a point 1 metre away from it is Show Answer

Q81) A magnetic needle lying parallel to a magnetic field required W units of work to turn it through 60°. The torque required to maintain the needle in this position will be Show Answer

Q82) Which of the following particles will describe the smallest circle when projected with the same velocity perpendicular to the magnetic field? Show Answer

Q83) An electron moving with a uniform velocity along the positive x-direction enters a magnetic field directed along the positive y-direction. The force on the electron is directed along Show Answer

Q84) A solenoid consists of 100 turns of wire and has a length of 10.0 cm. The magnetic field inside the solenoid when it carries a current of 0.500 A will be Show Answer

Q85) The magnetic field on the axis of a long solenoid having n turns per unit length and carrying a current i is Show Answer

Q86) Potential energy of a bar magnet of magnetic moment M placed in a magnetic field of induction B such that it makes an angle θ with the direction of B is Show Answer

Q87) An electron is moving in the north direction. It experiences a force in vertically upward direction. The magnetic field at the position of the electron is in the direction of Show Answer

Q88) The magnetic moment of a circular coil carrying current is Show Answer

Q89) Two magnets have the same length and the same pole strength. But one of the magnets has a small hole at its center. Then Show Answer

Q90) A rectangular coil 20 cm×20 cm has 100 turns and carries a current of 1 A. It is placed in a uniform magnetic field B=0.5 T with the direction of magnetic field parallel to the plane of the coil. The magnitude of the torque required to hold this coil in this position is Show Answer

Q91) A vertical wire carrying a current in the upward direction is placed in horizontal magnetic field directed towards north. The wire will experience a force directed towards Show Answer

Q92) Two long parallel wires carry equal current i flowing in the same direction area at a distance 2d apart. The
magnetic field B at a point lying on the perpendicular line joining the wires and a distance x from the
midpoint is Show Answer

Q93) A current loop consists of two identical semicircular parts each of radius R, one lying in the x-y plane and the other in x-z plane. If the current in the loop is i. The resultant magnetic field due to the two semicircular part at their common centre is Show Answer

Q94) Two circular coils mounted parallel to each other on the same axis carry steady current.If an observer between the coil reports that one coil is carrying a counter clockwise current i1 and while other is carrying i2 current ,between two coil and there is, Show Answer

Q95) A current carrying loop is free to turn in a uniform magnetic field. The loop will them come into equilibrium when its plane is inclined at Show Answer

Q96) A circular coil having N turns is made from a wire of length L meter. If a current I ampere is passed through it and is placed in a magnetic field of Btesla, the maximum torque on it is Show Answer

Q97) The strength of the magnetic field around a long straight wire, carrying current, is Show Answer

Q98) Motion of a moving electron is not affected by Show Answer

Q99) An electron and a proton travel with equal speed in the same direction at 90° to a uniform magnetic field as this is switched on. They experience forces which are initially Show Answer

Q100) At a distance of 10 cm from a long straight wire carrying current, the magnetic field is 0.04 T. At the distance of 40 cm, the magnetic field will be Show Answer

Q101) If a current is passed in a spring, it Show Answer

Q102) A uniform magnetic field acts at right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of radius 2 cm. If the speed of the electrons is doubled, then the radius of the circular path will be Show Answer

Q103) Under the influence of a uniform magnetic field a charged particle is moving in a circle of radius R with
constant speed v. The time period of the motion Show Answer

Q104) A chare q coulomb moves in a circle at n revolutions per second and the radius of the circle is r metre.
Then the magnetic field at the centre of the circle is Show Answer

Q105) A metal wire of mass m slides without friction on two rails placed at a distance l aprt. The track lies in a uniform vertical magnetic field B. A constant current i flows along the rails across the wire and brack down the other rail. The acceleration of the wire is Show Answer

Q106) If a proton, deuteron and α-particle on being accelerated by the same potential difference enters perpendicular to the magnetic field, then the ratio of their kinetic energies is Show Answer

Q107) A uniform electric field and a uniform magnetic field exist in a region in the same direction. An electron is
projected with a velocity pointed in the same direction. Then the electron will Show Answer

Q108) A solenoid 1.5 m long and 0.4 cm in diameter possesses 10 turns/cm length. A current of 5 A falls through
it. The magnetic field at the axis inside the solenoid is Show Answer

Q109) Proton and α-particle are projected perpendicularly in a magnetic field, if both move in a circular path with same speed. Then ratio of their radii is Show Answer

Q110) The oscillating frequency of a cyclotron is 10 MHz. If the radius of its Dees is 0.5 m, then kinetic energy of a proton, which is accelerated by the cyclotron is Show Answer

Q111) An α particle and a proton travel with same velocity in a magnetic field perpendicular to the direction of their velocities. Find the ratio of the radii of their circular path Show Answer

Q112) A circular coil of 20 turns and radius 10 cm is placed in uniform magnetic field of 0.10 T normal to the plane of the coil. If the current in coil is 5 A, then the torque acting on the coil will be Show Answer

Q113) A charged particle is moving in a uniform magnetic field in a circular path. Radius of circular path is R. When energy of particle is doubled, then new radius will be Show Answer

Q114) A charged particle is projected in a plane perpendicular to a uniform magnetic field. The area bounded by the path described by the particle is proportional to Show Answer

Q115) A circular loop and a square loop are formed from the same wire and the same current is passed through them. Find the ratio of their dipole moments. Show Answer

Q116) A proton, a deuteron and an alpha particle with the same kinetic energy enter a region of uniform magnetic field B at right angles to the field. The ratio of the radii of their circular paths is Show Answer

Q117) A current carrying conductor produces Show Answer

Q118) A current carrying straight wire is kept along the axis of a circular loop carrying a current. The straight wire Show Answer

Q119) A straight wire carrying a current 10 A is bent into a semicircular arc of radius 5 cm. The magnitude of magnetic field at the centre is Show Answer

Q120) The magnetic field normal to the plane of a wire of n turns and radius r which carries a current i is measured on the axis of the coil at a small distance h from the centre of the coil. This is smaller than the magnetic field at the centre by the fraction Show Answer

Q121) An electron is moving on a circular path of radius r with speed v in a transverse magnetic field B.e/m for it will be Show Answer

Q122) Two free parallel wires carrying currents in the opposite directions Show Answer

Q123) The magnetic flux density B at a distance r from a long straight rod carrying a steady current varies with r as shown in figure. Show Answer

Q124) A charge particle of mass m and charge q enters a region of uniform magnetic field B perpendicular of its velocity v. The particle initially at rest was accelerated by a potential difference V (volts) before it entered the region of magnetic field. What is the diameter of the circular path followed by the charged particle in the region of magnetic field? Show Answer

Q125) A straight wire of length 0.5 metre and carrying a current of 1.2 ampere is placed in a uniform magnetic field of induction 2 tesla. The magnetic field is perpendicular to the length of the wire. The force on the wire is Show Answer

Q126) A proton, a deutron and a α- particle enter a magnetic field perpendicular to field with same velocity. What is the ratio of the radii of circular paths? Show Answer

Q127) A proton of energy 200 MeV enters the magnetic field of 5 T. If direction of field is from south to north and motion is upward, the force acting on it will be Show Answer

Q128) A current i flows in a circular coil of radius r. If the coil is placed in a uniform magnetic field B with its plane parallel to the field, magnitude of the torque that acts on the coil is Show Answer

Q129) The radius of a circular loop is r and a current i is flowing in it. The equivalent magnetic moment will be Show Answer

Q130) A coil carrying a heavy current and having large number of turns is mounted in a N-S vertical plane and a current flows in clockwise direction. A small magnetic needle at its centre will have its north pole in Show Answer

Q131) A moving charge will gain energy due to the application of Show Answer

Q132) A straight wire of mass 200 g and length 1.5 m carries a current of 2 A. It is suspended in mid-air by a uniform horizontal magnetic field B. The magnitude of B (in tesla) is Show Answer

Q133) A long hollow copper tube carries a current I. Then which of the following will be true? Show Answer

Q134) An electron enters a region where electrostatic field is 20N/C and magnetic field is 5T. If electron passes undeflected through the region, the velocity of electron will be Show Answer

Q135) Magnetic field intensity at the centre of coil of 50 turns, radius 0.5 m and carrying a current of 2 A is Show Answer

Q136) An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4/3 and 2/3, then the ratio of the currents passing through the wire will be Show Answer

Q137) When a charged particle enters a uniform magnetic field, its kinetic energy Show Answer

Q138) The force on a charged particle moving with a velocity v in a magnetic field B is not Show Answer

Q139) A long, straight, solid metal wire of radius 2 mm carries a current uniformly distributed over its circular cross-section. The magnetic field induction at a distance 2 mm from its axis is B. Then the magnetic field induction at distance 1 mm from axis will be Show Answer

Q140) When the current flowing in a circular coil is doubled and the number of turns of the coil in it is halved, the magnetic field at its centre will become Show Answer

Q141) A horizontal metal wire is carrying an electric current from the north to the south. Using a uniform magnetic field, it is to be prevented from falling under gravity. The direction of this magnetic field should be towards the Show Answer

Q142) The cyclotron frequency of an electron grating in a magnetic field of 1 T is approximately Show Answer

Q143) A cable carrying a direct current is burried in a wall which stands in a north-south plane. A horizontal compass needle on the west side of the wall is found to point towards south instead of north. The coil is laid Show Answer

Q144) An electron and a proton enter a magnetic field perpendicularly. Both have same kinetic energy. Which of the following is true? Show Answer

Q145) Radius of curvature of path of the charged particle in the uniform magnetic field is directly proportional to Show Answer

Q146) The electron movie toward the east enters a magnetic field directed towards the north.The force on the electric field will be directed Show Answer

Q147) Four charged particles are projected perpendicularly into the magnetic field with equal. Which will have minimum frequency? Show Answer

Q148) An electron moving around the nucleus with an angular momentum l has a magnetic moment Show Answer

Q149) A uniform electric field and a uniform magnetic field are produced, pointing in the same direction. If an electron is projected with its velocity pointing in the same direction Show Answer

Q150) Two long parallel wires P and Q are both perpendicular to the plane of the paper with distance 5 m between them. If P and Q carry current of 2.5 amp and 5 amp respectively in the same direction, then the magnetic field at a point half way between the wires is Show Answer

Q151) A moving coil galvanometer gives full scale deflection, when a current of 0.005 A is passed through its coil. It is converted into a voltmeter reading upto 5V by using an external resistance of 975 Ω. What is the resistance of the galvanometer coil? Show Answer

Q152) Two long wires are hanging freely. They are joined first in parallel and then in series and then are connected with a battery. In both cases, which type of force acts between the two wires Show Answer

Q153) In order to increase the sensitivity of a moving coil galvanometer, one should decrease Show Answer

Q154) A current i A flows along an infinitely long straight thin walled tube, then the magnetic induction at any point inside the tube is Show Answer

Q155) A wire of length 2 m carrying a current of 1 A is bent to form a circle, the magnetic moment of the coil is Show Answer

Q156) A loosely wound helix made of stiff wire is mounted vertically with the lower end just touching a dish of mercury. When a current from a battery is started in the coil through the mercury Show Answer

Q157) The resultant magnetic moment of neon atom will be Show Answer

Q158) If two parallel wires carry current in opposite directions Show Answer

Q159) A very high magnetic field is applied to stationary charge then magnetic charge experiences Show Answer

Q160) A charged particle enters in a magnetic field whose direction is parallel to velocity of the particle, then the speed of this particle Show Answer

Q161) A proton and a deuteron with the same initial kinetic energy enter a magnetic field in a direction perpendicular to the direction of the field. The ration of the radii of the circular trajectories described by them is Show Answer

Q162) A straight wire carrying current i,is turned into a circular loops .If the magnitude of magnetic movement associate with in MKS unit is M the length of wire will be Show Answer

Q163) In a current carrying long solenoid ,the field produces does not depend upon Show Answer

Q164) The Magnetic induction of the centre of current carrying radius r,is Show Answer

Q165) One Tesla is equal to Show Answer

Q166) Maximum kinetic energy of the positive ion in the cyclotron is Show Answer

Q167) Which of the following graph represents the variation of magnetic flux density B with distance r for a straight long wire carrying an electric current? Show Answer

Q168) The direction of induced magnetic field dB due to current element i dL ,at a point of distance r from it ,when a current i passes through a long conductor is in the direction Show Answer

Q169) A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point Q lies to the west at the same distance. The magnetic field at P is Show Answer

Q170) A small circular flexible loop of wire of radius r carries a current I. It is placed in a uniform magnetic field B. The tension in the loop will be doubled if Show Answer

Q171) A current carrying rectangular coil is placed in a uniform magnetic field. In which orientation, the coil will not tend to rotate Show Answer

Q172) The dimension of the magnetic field intensity B is Show Answer

Q173) Biot-Savart’s law may be represented in vector form as Show Answer

Q174) A current carrying loop is placed in uniform magnetic field.the torque acting on it does not depend upon Show Answer

Q175) Which of the following graphs represent variation of magnetic field B with distance r for a straight long wire carrying current? Show Answer

Q176) The ratio of magnetic field and magnetic moment at the centre of current carrying circular loop is x.when the both the current and radius is doubled then the ratio will be Show Answer

Q177) A particle is moving in a uniform magnetic field, then Show Answer

Q178) A large magnet is broken into two pieces so that their lengths are in the 2:1. The pole strengths of the two pieces will have ratio Show Answer

Q179) Consider the following statement regarding a charged in a particle.
I) starting with zero velocity ,it accelerate in direction perpendicular to its magnetic field .
II) While deflecting to its magnetic field ,its energy gradually increases
III)only the component of magnetic field perpendicular to the direction of motion of the charged particle is effective deflecting it
IV)Direction of deflecting force on moving charge particle is perpendicular to its velocity of these statement Show Answer

Q180) Toroid is Show Answer

Q181) Two long parallel wires are at a distance 2d apart. They carry steady equal current flowing out of the plane of the paper as shown. The variation of the magnetic field along the line XX'is given by Show Answer

Q182) A voltmeter has resistance of 2000 Ω and it can measure upto 2V. If we want to increase its range by 8V, then required resistance in series will be Show Answer

Q183) The direction of magnetic lines of forces close to a straight conductor carrying current will be Show Answer

Q184) The magnetic field at the centre of current carrying coil is Show Answer

Q185) A microammeter has a resistance of 100 Ω and full scale range of 50μ A. It can be used as a voltmeter of as a higher range ammeter provided a resistance is added to it. Pick the correct range and resistance combinations Show Answer

Q186) A charge Q is uniformly distributed over the surface of non-conducting disc of radius R. The disc rotates about an axis perpendicular to its plane and passing through its centre with an angular velocity ω. As a result of this rotation a magnetic field of induction B is obtained at the centre of the disc. If we keep both the amount of charge placed on the disc and its angular velocity to be constant and very the radius of the disc then the variation of the magnetic induction at the centre of the disc will be represented by the figure Show Answer

Q187) Two wires of same length are shaped into a square and a circle. If they carry same current, ratio of the magnetic moment is Show Answer

Q188) Lorentz force can be calculated by using the formula Show Answer

Q189) An electron is travelling along the x-direction. It encounters a magnetic field in the y-direction. Its subsequent motion will be Show Answer

Q190) A current flows in a conductor from east to west. The direction of the magnetic field at a point above the conductor is Show Answer

Q191) A proton and an electron both moving with the same velocity v enter into region in a magnetic field directed perpendicular to the velocity of the particle.They will now move in circular orbits such that Show Answer

Q192) Two similar coils are kept perpendicular such that their centres coincide.at the centre, find the ratio of magnetic field due to one coil and the resultant magnetic field by both coils,if the same currentis flown. Show Answer

Q193) A current carries small loop behaves like small magnet.If A be its area and M its magnetic moment ,the current in loop will be Show Answer

Q194) A moving coil galvanometer has N number of turns in a coil of effective area A, it carries a current I. The magnetic field B is radial. The torque acting on the coil is Show Answer

Q195) When a magnetic field is applied in a direction perpendicular to the direction of cathode rays, then their Show Answer

Q196) The current is flowing in south direction along a power line.The direct of magnetic field above the power line (neglecting earth's field) is Show Answer

Q197) Two thin,long parallel wires,seperated by distance d carry a current of i ampere in the same direction.They will Show Answer

Q198) A uniform magnetic field B and a uniform electric field E, act in a common region.An electron is entering this region of space.The correct arrangement for it to escape undeviated is Show Answer

Q199) Which of the following statement is true. Show Answer

Q200) A wire of length l is bent in the from of a circular coil of some turns. A current i flows through the coil. The coil is placed in a uniform magnetic field B. The maximum torque on the coil can be Show Answer

Q201) Field inside a solenoid is Show Answer

Q202) Two long parallel wires carry equal current i flowing in the same direction area at a distance 2d apart.The magnetic field B at the point lying on the perpendicular line joining the wires and distance x from the midpoint is Show Answer

Q203) A charged particle is moving with velocity v in a magnetic field of induction B. The force on the particle will be maximum when Show Answer

Q204) A particle of mass m and charge q is placed at a rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is Show Answer

Q205) A small coil of N turns has area A and a current I flows through it. The magnetic dipole moment of this coil will be Show Answer

Q206) A positively charged particle moving due east enters a region of uniform magnetic field directed vertically upwards. The particle will Show Answer

Q207) A charged particle moving in a uniform magnetic field penetrates layer of lead and there by loss one-half of its kinetic energy. How does the radius of curvature of its path change? Show Answer

Q208) A current I flows along the length of an infinitely long, straight, thin walled pipe. Then Show Answer

Q209) The deflection in a moving coil galvanometer is Show Answer

Q210) Two infinitely long parallel wires carry equal current in same direction. The magnetic field at a mid point in between the two wires is Show Answer

Q211) A beam of electrons passes undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off and the same magnetic field is maintained the electrons move Show Answer

Q212) For the magnetic field to be maximum due to a small element of current carrying conductor at a point, the angle between the element and the line joining the element to the given point must be Show Answer

Q213) An electron enters a magnetic field whose direction is perpendicular to the velocity of the electron. Then Show Answer

Q214) A charged particle moving in a magnetic field experiences a resultant force Show Answer

Q215) A strong magnetic field is applied on a stationary electron, then Show Answer

Q216) A tangent galvanometer is connected directly to an ideal battery. If the number of turns in the coil is doubled, the deflection will Show Answer

Q217) A magnetic field can be produced by Show Answer

Q218) If a long hollow copper pipe carries a direct current, the magnetic field associated with the current will be Show Answer

Q219) Graph of force per unit length between two long parallel currents carrying conductor and the distance between them is Show Answer

Q220) The ratio of the magnitude field at the centre of a current carrying coil of the radius a and at a distance ‘a’ from centre of the coil and perpendicular to the axis of coil is Show Answer

Q221) Identify the correct statement from the following Show Answer

Q222) A one metre long wire is lying at right angles to the magnetic field. A force of 1 kg wt. is acting on it in a magnetic field of 0.98 tesla. The current flowing in it will be Show Answer

Q223) A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is Show Answer

Q224) A proton, a deuteron and an α- particle with the same kinetic energy enter a region of uniform magnetic field moving at right angles to B. What is the ratio of the radii of their circular paths? Show Answer

Q225) A thin disc having radius r and charge q distributed uniformly over the disc is rotated n rotations per second about its axis. The magnetic field at the centre of the disc is Show Answer

Q226) A charge particle moving in magnetic field B, has the components of velocity along B as well as perpendicular to B. The path of the charge particle will be
Show Answer

Q227) An electron is moving along the positive X-axis. If the uniform magnetic field is applied parallel to the negative Z-axis, then
A. the electron will experience magnetic force along positive Y-axis.
B. the electron will experience magnetic force along negative Y-axis.
C. the electron will not experience any force in magnetic field
D. the electron will continue to move along the positive X-axis.
E. the electron will move along circular path in magnetic field.
Choose the correct answer from the options given below.
Show Answer

Q228) Given below are two statements: One is labelled as
Assertion A and the other is labelled as Reason R Assertion A An electric fan continues to rotate for some time after the current is switched off.
Reason R Fan continues to rotate due to inertia of motion.
In the light of above statements. choose the most appropriate answer from the options given below Show Answer

Q229) The source of time varying magnetic field
A. a permanent magnet
B. an electric field changing linearly with time
C. direct current
D. a decelerating charge particle
E. an antenna fed with a digital signal
Choose the correct answer from the options given
Show Answer

Q230) A long straight wire of circular cross-section (radius a) is carrying steady current I. The current I uniformly distributed across this cross-section. The magnetic field is Show Answer

Q231) A long conducting wire having a current I flowing through it, is bent into a circular coil of N turns. Then it is bent into a circular coil of n turns. The magnetic field is calculated at the centre of coils in both the cases. The ratio of the magnetic field in first case to that of second case is Show Answer

Q232) A circular loop of radius r is carrying current IA. The ratio of magnetic field at the centre of circular loop and at a distance r from the centre of the loop on its axis is Show Answer

Q233) A solenoid of 1200 turns is wound uniformly in a single layer on a glass tube 2m long and 0.2m in diameter. The magnetic intensity at the centre of the solenoid when a current of 2A flows through it is Show Answer

Q234) An infinitely long hollow conducting cylinder with radius R carries a uniform current along its surface. Choose the correct representation of magnetic field B as a function of radial distance (r) from the axis of cylinder. Show Answer

Q235) A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of magnetic field will be equal to Show Answer

Q236) A long straight wire with a circular cross-section having radius R, is carrying a steady current I. The current I is uniformly distributed across this cross-section. Then, the variation of magnetic field due to current I with distance r (r< R) from its centre will Show Answer

Q237) The magnetic field at the centre of a circular coil of radius r, due to current I flowing through it, is B. The magnetic field at a point along the axis at a distance r/2 from the centre is Show Answer

Q238) A coil having N turns is wound tightly in the form of a spiral with inner and outer radii a and b, respectively. Find the magnetic field at centre, when a current I passes through coil
Show Answer

Q239) A current of 1.5 A is flowing through a triangle, of side 9 cm each. The magnetic field at the centroid of the triangle is (Assume that, the current is flowing in the clockwise direction.) Show Answer

Q240) The fractional change in the magnetic field intensity at a distance r from centre on the axis of current carrying coil of radius a to the magnetic field intensity at the centre of the same coil is
(Take, r< a) Show Answer

Q241) Magnetic fields at two points on the axis of a circular coil at a distance of 0.05 m and 0.2 m from the centre are in the ratio 8: 1. The radius of coil is Show Answer

Q242) A charge Q is uniformly distributed over the surface of non-conducting disc of radius R. The disc rotates about an axis perpendicular to its plane and passing through its centre with an angular velocity @ As a result of this rotation, a magnetic field of induction B is obtained at the centre of the disc.
If we keep both the amount of charge placed on the disc and its angular velocity to be constant and vary the radius of the disc, then the variation of the magnetic induction at the centre of the disc will be represented by the figure
Show Answer

Q243) A current I flows in an infinitely long wire with cross-section in the form of a semi-circular ring of radius R. The magnitude of the magnetic induction along its axis is Show Answer

Q244) Two long parallel wires are at a distance 2d carry steady equal current flowing out of the plane of the paper as shown. The variation of the magnetic field along the line xx' is given by
Show Answer

Q245) A long straight wire of radius a carries a steady current I. The current is uniformly distributed across its cross-section. The ratio of the magnetic field at a /2 and 2 a is Show Answer

Q246) A current I flows along the length of an infinitely long, straight, thin walled pipe. Then, Show Answer

Q247) A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil will be Show Answer

Q248) The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 μT. What will be its value at the centre of the loop?
Show Answer

Q249) The ratio of magnetic field at the centre of a current carrying coil of radius r from the magnetic field at distance r from the centre of coil on its axis is √x: 1. The value of x is Show Answer

Q250) An electron is allowed to move with constant velocity along the axis of current carrying straight solenoid.
A. The electron will experience magnetic force along the axis of the solenoid.
B. The electron will not experience magnetic force. C. The electron will continue to move along the axis of the solenoid.
D. The electron will be accelerated along the axis of the solenoid.
E. The electron will follow parabolic path-inside the solenoid.
Choose the correct answer from the options given below.
Show Answer

Q251) Two charged particles, having same kinetic energy, are allowed to pass through a uniform magnetic field perpendicular to the direction of motion. If the ratio of radii of their circular path is 6: 5 and their respective masses ratio is 9: 4. Then, the ratio of their charges will be Show Answer

Q252) Given below are two statements
Statement I The electric force changes the speed of the charged particle and hence changes its kinetic energy, whereas the magnetic force does not change the kinetic energy of the charged particle. Statement II The electric force accelerates the positively charged particle perpendicular to the direction of electric field. The magnetic force accelerates the moving charged particle along the direction of magnetic field. In the light of the above statements, choose the most appropriate answer from the options given below Show Answer

Q253) A charged particle moves along circular path in a uniform magnetic field in a cyclotron. The kinetic energy of the charged particle increases to 4 times its initial value. What will be the ratio of new radius to the original radius of circular path of the charged particle Show Answer

Q254) A proton and an alpha particle of the same velocity enter in a uniform magnetic field which is acting perpendicular to their direction of motion. The ratio of the radii of the circular paths described by the alpha particle and proton is Show Answer

Q255) Given below are two statements, one is labelled as Assertion (A) and the other is labelled as Reason (R). TOO Assertion (A) In a uniform magnetic field, speed and energy remains the same for a moving charged particle. Reason (R) Moving charged particle experiences 500 magnetic force perpendicular to its direction of motion. Show Answer

Q256) Two ions of masses 4 amu and 16 amu have charges +2 and +3e, respectively. These ions pass through the region of constant perpendicular magnetic field. The kinetic energy of both ions is same. Then, Show Answer

Q257) Two ions having same mass have charges in the ratio 1:2. They are projected normally in a uniform. magnetic field with their speeds in the ratio 2: 3. The ratio of the radii of their circular trajectories is Show Answer

Q258) A negative test charge is moving near a long straight wire carrying a current. The force acting on the test charge is parallel to the direction of the current. The or motion of the charge is:
Show Answer

Q259) A charged particle with charge q enters a region of constant, uniform and mutually orthogonal fields E and B with a velocity v perpendicular to both E and B and comes out without any change in magnitude or direction of v. Then, Show Answer

Q260) A charged particle moves through a magnetic field perpendicular to its direction. Then, Show Answer

Q261) A charged particle of mass m and charge q travels on a circular path of radius r that is perpendicular to a magnetic field B. The time taken by the particle to complete one revolution is
Show Answer

Q262) A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity, then Show Answer

Q263) If an electron and a proton having same momenta enter perpendicularly to a magnetic field, then Show Answer

Q264) The time period of a charged particle undergoing a circular motion in a uniform magnetic field is independent of its Show Answer

Q265) A singly ionised magnesium atom (A =24) ion is -accelerated to kinetic energy 5 keV and is projected perpendicularly into a magnetic field B of the magnitude 0.5 T. The radius of path formed will be ......... cm. Show Answer

Q266) Two long current carrying conductors are placed 1800s parallel to each other at a distance of 8 cm between them. The magnitude of magnetic field produced at mid-point between the two conductors due to current flowing in them is 300 μT. The equal current flowing in the two conductors is Show Answer

Q267) A loop of flexible wire of irregular shape carrying current is placed in an external magnetic field. Identify the effect of the field on the wire. Show Answer

Q268) A charged particle going around in a circle can be considered to be a current loop. A particle of mass m carrying charge q is moving in a plane with speed v under the influence of magnetic field B. The magnetic moment of this moving particle Show Answer

Q269) A circular coil having N turns and radius r carries a current I. It is held in the XZ-plane in a magnetic field Bi. The torque on the coil due to the magnetic field (in N-m) is Show Answer

Q270) A square loop is carrying a steady current I and the magnitude of its magnetic dipole moment is m. If this square loop is changed to a circular loop and it carries the same current, the magnitude of the magnetic dipole moment of circular loop (in A-m) will be Show Answer

Q271) Two thin, long, parallel wires, separated by a distance d carry a current of I ampere in the same direction. They will
Show Answer

Q272) If a current is passed through a spring, then the nispring will Show Answer

Q273) The current sensitivity of moving coil galvanometer is increased by 25%. This increase is achieved only by changing the number of turns of coil and area of cross-section of the wire while keeping the resistance of galvanometer coil constant. The percentage change in the voltage sensitivity will be Show Answer

Q274) Given below are two statements
Statement I If the number of turns in the coil of a moving coil galvanometer is doubled then the current sensitivity becomes double.
Statement II Increasing current sensitivity of a moving coil galvanometer by only increasing the number of turns in the coil will also increase its voltage sensitivity in the same ratio
In the light of the above statements, choose the correct answer from the options given below:
Show Answer

Q275) Certain galvanometers have a fixed core made of non magnetic metallic material. The function of this metallic material is Show Answer

Q276) The current sensitivity of a galvanometer can be increased by
A. decreasing the number of turns
B. increasing the magnetic field
C. decreasing the area of the coil
D. decreasing the torsional constant of the spring
Choose the most appropriate answer from the options given below.
Show Answer

Q277) Consider a galvanometer shunted with 5 resistance and 2% of current passes through it. What is the resistance of the given galvanometer? Show Answer

Q278) The resistance of a galvanometer is 50 ohm and the maximum current which can be passed through it is 0.002 A. What resistance must be connected to it in order to convert it into an ammeter of range 0-0.5 A? Show Answer

Q279) A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per order that each division reads 1 V, the resistance in Ohms needed to be connected in series with the coil will be Show Answer

Q280) If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a Show Answer