Practice Test

Q1) The arms of magnetometer in the tan B position (Broad -side on ) are placed along : Show Answer

Q2) Points A and B are situated along the extended axis of a 2 cm long bar magnet at a distance x and 2x cm respectively from the pole nearer to the points. The ratio of the fields at A and B will be : Show Answer

Q3) If a bar magnet is placed with its north pole pointing towards north of earth, the neutral points are located : Show Answer

Q4) The magnetic fields at a given distance from a short bar magnetic in longitudinal and transverse positions are in the ratio : Show Answer

Q5) The line on surface of earth joining the points where H has same value is : Show Answer

Q6) Two identical thin bar magnets each of length l and pole strength m are placed at right angles to each other with north pole of one touching south pole of other, the magnetic moment of the system is : Show Answer

Q7) A magnet is placed vertically on a paper. Then the neutral point obtained on the paper is : Show Answer

Q8) A steel wire of length l has a magnetic moment M. It is then bent into a semi-circular arc. The new magnetic moment is : Show Answer

Q9) The arms of magnetometer in the end-on ( tan A) position are placed along : Show Answer

Q10) Time period of a freely suspended magnet does not depend upon : Show Answer

Q11) A magnetic needle suspended horizontally by unspun silk thread oscillates in the horizontal plane because of the restoring force originating mainly from : Show Answer

Q12) A very thin steel needle with magnetic moment M and length l is cut into two equal pieces. If the time period of vibration in earth's field before cutting the needle is T, the time period of each half after cutting it is : Show Answer

Q13) Two bar magnets when suspended with their norths along the magnetic meridian one above the other give a time period of 12s. When weaker of the two is reversed the period increases by 4s. Ratio of their moments is : Show Answer

Q14) A dip needle in a plane perpendicular to the magnetic meridian will remain : Show Answer

Q15) Susceptibility is positive but smaller for : Show Answer

Q16) A magnet is vibrated horizontally in a plane perpendicular to the magnetic meridian, its frequency of vibration is : Show Answer

Q17) The time period of horizontally suspended magnetic needle at the magnetic pole of earth is : Show Answer

Q18) A magnetic needle is kept in a non-uniform magnetic field. It experiences : Show Answer

Q19) Permeability of a diamagnetic is : Show Answer

Q20) For paramagnetics : Show Answer

Q21) A vibration magnetometer consists of two identical bar magnets placed one over the other such that they are mutually perpendicular and bisect each other. The time period of combination is 4s. If one of the magnets is removed, find the period of other ? Show Answer

Q22) Isoclinic are the lines joining the places of : Show Answer

Q23) Isogonic lines represents the lines of : Show Answer

Q24) Agonic lines are : Show Answer

Q25) Aclinic lines are of : Show Answer

Q26) Which of the following substances has negative permeability and very large value of susceptibility ? Show Answer

Q27) Which of the following properties has low value for ferrites ? Show Answer

Q28) A magnet of pole strength m is divided into four equal parts so that the length as well as the breath of each part is half of the original magnet. Then the pole strength of each is : Show Answer

Q29) A magnet of pole strength m is divided into four equal parts so that the length as well as the breath of each part is half of the original magnet. Then the dipole of each is : Show Answer

Q30) Imaginary lines joining points of equal declination are called : Show Answer

Q31) A magnet oscillates in earth's field with a time period T. If its mass is quadrupled, then its new time period will be : Show Answer

Q32) A bar magnet with poles 25.0 cm apart and of pole strength 14.4 Am rests with its center on a frictionless point. It is held in equilibrium at 60 degrees to a uniform magnetic field of induction 0.25 T by applying a force F at right angle to the axes, 12 cm from its pivot. The magnitude of the force is : Show Answer

Q33) A circular coil of radius 5.0 cm having 30 turns, lies in a horizontal plane. In carries a current of 5 A in clockwise sense when viewed from above. The magnetic moment of the coil is : Show Answer

Q34) The value of Bohr-magneton is Show Answer

Q35) The magnetic permeability of vacuum in C.G.S. system is : Show Answer

Q36) To shield an instrument from the external magnetic field, it is placed inside a cabin made from : Show Answer

Q37) The magnetic compass is not useful for navigation near the magnetic poles, since there : Show Answer

Q38) A vibration magnetometer is placed at the south pole, then the time period will be : Show Answer

Q39) A ferromagnetic material is heated above its curie temperature. Which one is a correct statement ? Show Answer

Q40) A compass needle when placed at a geomagnetic pole stays along : Show Answer

Q41) When a ferromagnetic material is taken through a hysteresis cycle, the magnetic susceptibility cannot be : Show Answer

Q42) Electromagnets are made of soft iron because soft iron has : Show Answer

Q43) Permanent magnets are made of steel because steel has : Show Answer

Q44) A magnet is placed on a paper in a horizontal for locating neutral points. A dip circle is placed at the neutral point will horizontal at the : Show Answer

Q45) The isodynamic lines are loci of equal : Show Answer

Q46) A hydrogen atom is paramagnetic. A hydrogen molecule is : Show Answer

Q47) Ferromagnetic owe their properties to : Show Answer

Q48) The Hysteresis cycle for the material of a transformer is : Show Answer

Q49) The Hysteresis cycle for the material of permanent magnet is : Show Answer

Q50) Liquid and gases never show : Show Answer

Q51) A magnetic north pole is : Show Answer

Q52) A magnetic south pole is : Show Answer

Q53) An isolated magnetic pole is : Show Answer

Q54) A steel wire of length l has a magnetic moment M. It is then bent in L-shape at its mid point. The new magnetic moment is : Show Answer

Q55) A person is facing magnetic north. An electron in front of him flies horizontally towards the north and deflects towards east. He is in/at : Show Answer

Q56) A magnetic field is measured by : Show Answer

Q57) A ferromagnetic material goes through hysteresis loop, the magnetic susceptibility Show Answer

Q58) Which of the following graphs may best represent the current deflection relation in a tangent galvanometer ? Show Answer

Q59) A magnet 20 cm long with its poles concentrated at its ends is placed vertically with its North pole on the table. At a point due 20 cm south ( magnetic ) of the pole a neutral point is located. IF horizontal component of the earth's field is H = 0.3 gauss, then the pole strength of the magnet is nearly : Show Answer

Q60) A bar magnet suspended by a horse's hair lies in the magnetic meridian where there is no twist in the hair, on turning the upper end of the hair through 150 degree, the magnet is deflected through 30 degree from the meridian. Then, the angle through which the upper end of the hair has to be twisted to deflect the magnet through 90 degree from the meridian is : Show Answer

Q61) A direct current I flows in a long straight conductor whose cross-section has a form of a thin half ring of radius R. The same current flows in opposite direction along a thin conductor placed on the axis of first conductor, then the magnetic interaction force between the conductors to a unit of their length is : Show Answer

Q62) A vibration magnetometer consists of two identical bar magnets placed one above the other such that they are mutually perpendicular and bisect each other. The time period of oscillation in a horizontal magnetic field is 4s. If one of the magnets is taken away, then time period of oscillation of the other magnet in the same field is : Show Answer

Q63) A magnet weights 75 g and its magnetic moment is 300 c.g.s units. The density of the material of the magnet is 7.9 g/c.c. The intensity of magnetisation is (in c.g.s units ) : Show Answer

Q64) A thin rectangular magnet suspended freely has a period of oscillation of 4s. What will be the period of oscillation, if the magnet is broken into two halves ( each having half the original length ) one of the piece is made to oscillate in the same field ? Show Answer

Q65) An iron bar of length 10 cm and diameter 2 cm is placed in a magnetic field of intensity 10 oersted with its length parallel to the direction of the field. The magnetic moment produced in the bar if permeability of its material is 629 is : Show Answer

Q66) A metal wire of mass m slides without friction on two rails spaced at a distance d apart. The track lies in a vertical uniform field of induction B. A constant current I flows along one rail, across the wire and black down the other rail. The speed of the wire as function of time assuming it to be at rest initially : Show Answer

Q67) A long solenoid of length 0.4 m and having 500 turns of wire carries a current of 3 A. A thin coil having 10 turns of wire and radius of 0.01m carries a current of 0.4 A. Calculate the torque required to hold the coil in the middle of the solenoid with its axis perpendicular to the axis of the solenoid : Show Answer

Q68) An irregular closed loop carrying a current has shape that the entire loop cannot lie in a single plane. If this loop is placed in a uniform magnetic field, the force acting on the loop : Show Answer

Q69) A coil having N turns is wound tightly in the form a spiral with inner and outer radii a and respectively. When a current I passes through the coil, the magnetic field at the center is : Show Answer

Q70) Two north poles of pole strengths 0.4 Am and 6.4 Am are separated by 10 cm. The distance of the neutral points from 0.4 A m is : Show Answer

Q71) A magnet of magnetic moment M oscillating freely in earth's horizontal field makes n oscillations per minute. If the magnetic moment is quadrupled and the earth's field is doubled, the number of oscillations made per minute would be : Show Answer

Q72) The distances of two points on the axis of a magnet from its center are 10 cm and 20 cm respectively. The ratio of magnetic field at these points is 125 : 1. The length of the magnet is : Show Answer

Q73) If a bar magnet of magnetic moment of 80 units be cut into two halves of equal lengths, the magnetic moment of the each half will be : Show Answer

Q74) A circular coil of diameter 0.07 m has 24 turns of wire which carry current of 0.75 A. The magnetic moment of the coil is : Show Answer

Q75) The time period of oscillation of a magnet in a vibration magnetometer is 1.5 second. The time period of oscillation of another magnet similar in size, shape and mass but having one-fourth magnetic moment than that of the first magnet oscillating at same place will be : Show Answer

Q76) In two separate experiments, the neutral points due to two small magnets are a distance of r and 2r in broad side on position. The ratio of their magnetic moments will be : Show Answer

Q77) The magnetic field at a point x on the axis of a small bar magnet is equal to the field at a point y on the equator of the same magnet. The ratio of the distances of x and y from the center of the magnet is : Show Answer

Q78) If the ratio of earth's magnetic filed is 2 : 3, then the ratio of time periods of a magnet will be :
Show Answer

Q79) Points A and B are situated perpendicular to the axis of a 2 cm long bar magnet at large distances x and 3x from its center on opposite sides. The ratio of the magnetic fields at A and B will be approximately equal to : Show Answer

Q80) The length of magnet is large as compared to a width and breadth. The time period of its oscillation in a vibration magnetometer is 2s. The magnet is cut along its length into three equal parts and these parts are then placed on each other with their like poles together. The time period of this combination will be : Show Answer

Q81) The main use of studying the hysteresis curve for a given material is to estimate : Show Answer

Q82) A bar magnet is held perpendicular to a uniform magnetic field. If the torque acting on the magnet is to be halved by rotating it, then angle by which it is to be rotated is : Show Answer

Q83) Due to the earth's magnetic field, charged cosmic ray particles : Show Answer

Q84) A moving charge will produce : Show Answer

Q85) The magnetic susceptibility does not depend upon the temperature in : Show Answer

Q86) A tangent galvanometer is used to measure : Show Answer

Q87) The plane of the coil of a tangent galvanometer is vertical and perpendicular to the magnetic meridian. When a current is passed through the coil of the galvanometer, the magnetic needle deflects by : Show Answer

Q88) Which of the following is a paramagnetic group : Show Answer

Q89) In a deflection magnetometer, the external magnet should be replaced : Show Answer

Q90) Curie temperature of iron is the temperature below which it is : Show Answer

Q91) The period of oscillations of magnet is 2s. When it is remagnetised so that the pole strength is 4 times, its period will be : Show Answer

Q92) The magnetic field of earth is due to : Show Answer

Q93) A diamagnetic substance is placed in a magnetic field of a bar magnet. Then it is : Show Answer

Q94) A diamagnetic material in a magnetic field moves : Show Answer

Q95) According to Curie's law, the magnetic susceptibility of a substance, at an absolute temperature T, is proportional to : Show Answer

Q96) A frog can be leviated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as : Show Answer

Q97) The magnetic field lines due to a bar magnet are correctly shown in : Show Answer

Q98) The magnetic resonance imaging (MRI) is based on the phenomenon of : Show Answer

Q99) Liquid oxygen remains suspended between two poles of a magnet because it is : Show Answer

Q100) At which place earth's magnetic field becomes horizontal ? Show Answer

Q101) The pole strength of a bar magnet is 48 ampere-meter and the distance between its pole is 25 cm. The amount of the couple by which it can be placed at an angle 30 degrees with the uniform intensity of flux density 0.15 newton / ampere-meter will be: Show Answer

Q102) Above curie temp : Show Answer

Q103) Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature then it will show : Show Answer

Q104) A vibration magnetometer placed in magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of 2 sec in earth's horizontal magnetic field of 24 microtesla. When a horizontal field of 18 microtesla is produced opposite to earth's field by placing a current carrying wire, the new time period of magnet will be : Show Answer

Q105) There are four light-weight-rod samples A, B, C, D separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted :
(i) A is freely repelled.
(ii) B is freely repelled.
(iii) C is strongly attracted.
(iv) D remains unaffected.
Which one of the following is true ? Show Answer

Q106) The magnetic needle at magnetic pole becomes Show Answer

Q107) A current I is flowing in a conductor of length l. When it is bent in the form of a loop then its magnetic moment will be Show Answer

Q108) The resultant magnetic moment due to two current carrying concentric coils of radius r, mutually perpendicular to each other will be : Show Answer

Q109) Magnetic fields do not interact with Show Answer

Q110) Two bar magnets of the same mass, same length and breadth but having magnetic moment M and 2M are joined together pole for pole and suspended by a string. The time period of assembly in a magnetic field of strength H is 3 seconds. If now the polarity of one of the magnets is reversed and the combination is again made to oscillate in the same field, the time of oscillation is : Show Answer

Q111) A bar magnet is oscillating in earth's magnetic field with a period T. What happens to its period and motion if its mass is quadrupled ? Show Answer

Q112) The material of a permanent magnet has Show Answer

Q113) A tangent galvanometer is most sensitive when the deflection is around Show Answer

Q114) Force between two identical short bar magnets whose centers are r metre apart is 8.1 N, when their axes are long the same line. If separation is increased to 3r and the axis are rearranged perpendicularly, the force between them would become Show Answer

Q115) The magnetic needle of an oscillation magnetomter makes 10 oscillations per minute under the action of earth's magnetic field alone. When a bar magnet is placed at some distance along the axis of the needle, it makes 14 oscillations per minute. If the bar magnet is turned so that its poles interchange their positions, then the new frequency of oscillations of the needle is Show Answer

Q116) A dip needle vibrates in the vertical plane perpendicular to magnetic meridian. The time period of vibration is found to be 2 seconds. The same needle is then allowed to vibrate in the horizontal plane and time period is again found to be 2 seconds. Then the angle of dip is Show Answer

Q117) A thin rectangular magnet suspended freely has a period of oscillation of 4s. If it is broken into two equal halves, the period of oscillation of each half will be : Show Answer