Practice Test

Q1) Pick out the longest wavelength from the following types of radiations Show Answer

Q2) The displacement current flows in the dielectric of a capacitor when the potential difference across its plates Show Answer

Q3) Displacement current is continuous Show Answer

Q4) Range of frequencies allotted for commercial FM radio broadcast is Show Answer

Q5) The maximum electric field is Show Answer

Q6) The average energy density is Show Answer

Q7) At an instant when the magnetic field is along the y-axis, the electric field will be along Show Answer

Q8) Light is an electromagnetic wave. Its speed in vacuum is given by the expression Show Answer

Q9) If magnetic monopoles existed, then which of the following Maxwell's equations would be modified ? Show Answer

Q10) An electromagnetic radiation has an energy 14.4 keV. To which region of electromagnetic spectrum does it belong ? Show Answer

Q11) In FM, modulation is doubled. This is possible if frequency deviation is Show Answer

Q12) A step index fibre has a relative refractive index of 0.88%. What is the critical angle at the core - cladding interface ? Show Answer

Q13) The maximum range of ground or surface wave propagation depends on Show Answer

Q14) The maximum magnetic field is Show Answer

Q15) The maximum electric force on the electron is Show Answer

Q16) The maximum magnetic force on the electron is Show Answer

Q17) Velocity of Electromagnetic Waves in a medium depends upon Show Answer

Q18) According to Maxwell’s hypothesis, changing electric field gives rise to Show Answer

Q19) X-rays are produced by jumping of Show Answer

Q20) The wavelength of infrared rays is of the order of Show Answer

Q21) The speed of electromagnetic Wave in vacuum depends upon the source radiation. It Show Answer

Q22) Consider the following two statements regarding a linearly polarized plane electromagnetic wave
(i)Electric field and the magnetic field have equal average values
(ii)Electric energy and the magnetic energy have equal average values
Show Answer

Q23) The magnetic field between the plate of a capacitor where r>R is given by (where r is the distance from the axis of plates and R is the radius of each plate of capacitor) Show Answer

Q24) Which of the following relation is correct? Show Answer

Q25) Which is having minimum wavelength? Show Answer

Q26) Which of the following shows green house effect? Show Answer

Q27) 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

Q28) An electromagnetic radiation has an energy of 13.2 keV. Then the radiation belongs to the region of Show Answer

Q29) Out of the following electromagnetic radiation, which has the shortest wavelength? Show Answer

Q30) Maxwell in his famous equation of electromagnetism introduced the concept Show Answer

Q31) The correct sequence of the increasing wavelength of the given radiation sources is Show Answer

Q32) The shortest wavelength of X-rays emitted from an X-rays tube depends upon Show Answer

Q33) Hydrogen atom does not emit X-rays because Show Answer

Q34) According to Maxwell’s equation the velocity of light in any medium is expressed as Show Answer

Q35) An Electromagnetic Wave has Show Answer

Q36) In an Electromagnetic Wave, direction of propagation is in the direction of Show Answer

Q37) A point source of electromagnetic radiation has an average power output of 800 W. The maximum value of electric filed at a distance 4.0 m from the source is Show Answer

Q38) The oscillating electric and magnetic field vectors of electromagnetic wave are oriented along Show Answer

Q39) The electric field for a plane electromagnetic wave travelling in the positive z-direction is represented by which one of the following? Show Answer

Q40) Instantaneous displacement current of 1.0 A in the space between the parallel plate of 1 μF capacitor can be estabilished by changing potential difference of Show Answer

Q41) If a free electron is placed in the path of a plane electromagnetic wave, it will start moving along Show Answer

Q42) All components of the Electromagnetic Spectrum in vacuum have the same Show Answer

Q43) A. The wavelength of microwaves is greater than that of UV-rays.
B. The wavelength of IR rays is lesser than that of UV-rays.
C. The wavelength of microwaves is lesser than that of IR-rays.
D. Gamma rays have shortest wavelength in the Electromagnetic Spectrum.
Of the above statements Show Answer

Q44) The ozone layer absorbs Show Answer

Q45) Which of the following has zero average value in a plane electromagnetic wave? Show Answer

Q46) Primary constant of a transmission line are Show Answer

Q47) In frequency modulated wave Show Answer

Q48) Antenna is Show Answer

Q49) The losses in transmission lines are Show Answer

Q50) For maximum power transfer to the load, impedance of the detecting device must be equal to characteristic impedance of the transmission line Show Answer

Q51) The velocity of electromagnetic waves in a dielectric medium of constant 4 is Show Answer

Q52) The velocity of a particle at which the kinetic energy is equal to its rest energy is Show Answer

Q53) Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per sec. on the average at a target irradiated by this beam is Show Answer

Q54) The resistance of copper wire of diameter=2 mm is of the order of Show Answer

Q55) A 1000kHz carrier wave is modulated by audio signal of frequency range 100-5000Hz. Then the width of the channel in kHz is Show Answer

Q56) Frequency range for microwaves is Show Answer

Q57) If an electromagnetic wave is transmitted to the height equal to 150 km with maximum frequency 300 kHz and critical frequency 100 kHz, the skip distance is Show Answer

Q58) The maximum peak to peak voltage of an AM wire is 24 mV and the minimum peak to peak voltage is 8 mV. The modulation factor is Show Answer

Q59) The length of a half wave dipole at 30 MHz is Show Answer

Q60) For a body moving with relativistic speed, if the velocity is doubled, then Show Answer

Q61) In an amplitude modulated wave for audio frequency of 500 cycle/second, the appropriate carrier frequency will be Show Answer

Q62) The antenna current of an AM broadcast transmitter modulated by 50% is 11. Find the carrier current Show Answer

Q63) The velocity of electromagnetic wave in good conductor is Show Answer

Q64) A broken ligament is being ‘welded’ back in place using 20 ms pulses from a 0.5 W laser operating at a wavelength of 632 nm. The number of photons in 5 pulses of laser are Show Answer

Q65) Let A = light obtained by stimulated emission and B = light obtained by spontaneous, then Show Answer

Q66) Sinusoidal carrier voltage of frequency 1.5 MHz and amplitude 50 V is amplitude modulated by sinusoidal voltage of frequency 10 kHz producing 50% modulation. The lower and upper side-band frequencies in kHz are Show Answer

Q67) The velocity factor of a transmission line is x. If dielectric constant of the medium is 2.6, the value of x is Show Answer

Q68) A telephone link operating at a central frequency of 10 GHz is established. If 1% of this available then how many telephone channels can be simultaneously given when each telephone covering a band width of 5 kHz Show Answer

Q69) For good demodulation of AM signal of carrier frequency f, the value of RC should be Show Answer

Q70) The wavelength of red light from He-Ne laser is 633 nm in air but 474 nm in the aqueous humor inside the eye ball. Then the speed of red light through the aqueous humor is Show Answer

Q71) If both the length of an antenna and the wavelength of the signal to be transmitted are doubled, the power radiated by the antenna Show Answer

Q72) An AM wave has 1800 watt of total power content. For 100% modulation the carrier should have power content equal to Show Answer

Q73) What is the modulation index of an over modulated wave Show Answer

Q74) In AM, the centpercent modulation is achieved when Show Answer

Q75) What should be the velocity of an object so that it’s mass becomes twice of its rest mass? Show Answer

Q76) An antenna behaves as resonant circuit only when its length is Show Answer

Q77) 1000 kHz carrier wave is amplitude modulated by the signal frequency 200-4000 Hz. The channel width of this case is Show Answer

Q78) The transmission of high frequencies in a coaxial cable is determined by Show Answer

Q79) The energy of an electromagnetic wave contained in a small volume oscillates with Show Answer

Q80) Which of the following Maxwell's equation is valid for time varying conditions but not valid for static conditions Show Answer

Q81) In an electromagnetic wave, at an instant and at a particular position, the electric field is along the negative Z-axis and magnetic field is along the positive X-axis. Then, the direction of propagation of electromagnetic wave is Show Answer

Q82) A point source of 100 W emits light with 5% efficiency. At a distance of 5 m from the source, the intensity produced by the electric field component is Show Answer

Q83) An electromagnetic wave is transporting energy in the negative z-direction. At a certain point and certain time, the direction of electric field of the wave is along positive y-direction. What will be the direction of the magnetic field of the wave at that point and instant? Show Answer

Q84) Which of the following are true?
A. Speed of light in vacuum is dependent on the direction of propagation.
B. Speed of light in a medium is independent of the wavelength of light.
C. The speed of light is independent of the motion of the source.
D. The speed of light in a medium is independent of intensity.
Choose the correct answer from the options given below

Show Answer

Q85) Identify the correct statements from the following descriptions of various properties of electromagnetic waves:
(A) In a plane electromagnetic wave, electric field and magnetic field must be perpendicular to each other and direction of propagation of wave should be along electric field or magnetic field. (B) The energy in electromagnetic wave is divided equally between electric and magnetic fields.
(C) Both electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of wave.
(D) The electric field, magnetic field and direction of propagation of wave must be perpendicular to each other.
(E) The ratio of amplitude of magnetic field to the amplitude of electric field is equal to speed of light. Choose the most appropriate answer from the options given below.
Show Answer

Q86) The rms value of conduction current in a parallel plate capacitor is 6.9 μA. The capacity of this capacitor, if it is connected to 230 V AC supply with an angular frequency of 600 rad/s, will be Show Answer

Q87) A plane electromagnetic wave propagating along y-direction can have the following pair of electric field (E) and magnetic field (B) components. Show Answer

Q88) A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is Show Answer

Q89) For plane electromagnetic waves propagating in the z-direction, which one of the following combination the correct possible direction for field, respectively? Show Answer

Q90) The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is
Show Answer

Q91) An electromagnetic wave in vacuum has the electric is and magnetic fields E and B, which are always perpendicular to each other. The direction of polarisation is given by X and that of wave propagation by k. Then, Show Answer

Q92) A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is Show Answer

Q93) Electromagnetic waves are transverse in nature is
evident by
Show Answer

Q94) In a medium, the speed of light wave decreases to 0.2 times to its speed in free space. The ratio of relative permittivity to the refractive index of the medium is .... Show Answer

Q95) An electromagnetic wave of frequency
v=3.0 MHz passes from vacuum into a dielectric medium with permittivity & = 4.0. Then, Show Answer

Q96) Given below are two statements, one is labelled as :
Assertion (A) and the other is labelled as Reason (R). Assertion (A) EM waves used for optical communication have longer wavelengths than that of microwave, employed in Radar technology. Reason (R) Infrared EM waves are more energetic than microwaves, (used in Radar)
In the light of the above statements, choose the most appropriate answer from the options given below.
Show Answer

Q97) Which is the correct ascending order of wavelength? Show Answer

Q98) Arrange the following electromagnetic radiations quantum in the order of increasing energy.
A.Blue light
B. Yellow light
C. X-ray
D. Radio wave Show Answer

Q99) Which of the following are not electromagnetic Suley waves? Show Answer

Q100) We do not transmit low frequency signal to long distances because
(A)The size of the antenna should be comparable to signal wavelength which is unreal solution for a signal of longer wavelength.
(B)Effective power radiation by a long wavelength baseband signal would be high.
(C)We want to avoid mixing up signals transmitted by different transmitter simultaneously.
(D)Low frequency signal can be sent to long distances by superimposing with a high frequency wave as well
Therefore the most suitable option will be Show Answer

Q101) A 25m long antenna is mounted on an antenna tower. The height of the antenna tower is 75m. The wavelength (in m) of the signal transmitted by this antenna would be Show Answer

Q102) A message signal of frequency 5 kHz is used to modulate a carrier signal of frequency 2 MHz. The bandwidth for amplitude modulation is Show Answer

Q103) Choose the correct statements for amplitude modulation. Show Answer

Q104) A message of frequency 100 MHz and peak voltage 100 V is used to execute amplitude modulation on a carrier wave of frequency 300 GHz and peak voltage 400 V. The modulation index and difference between the two side bands frequencies are Show Answer

Q105) Choose the correct statement Show Answer