Electromagnetic Waves PYQs Set 2 (PDF)

Set 2 of 9 · Questions 31-60 of 244

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Mere Teacher · Previous Year Questions NEET Physics · Electromagnetic Waves · Set 2 (Q31-60)
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31. $Choose the correct sequence of the radiation sources in increasing order of the wavelength of electromagnetic waves produced by them.$ (1) $X-ray tube, Magnetron valve, Radioactive source, Sodium lamp$ (2) $Radioactive source, X-ray tube, Sodium lamp, Magnetron valve$ (3) $X-'́ay tube, Magnetron valve, Sodium lamp, Radioactive source$ (4) $Magnetron valve, Sodium lamp, X-ray tube, Radioactive source$ 32. $The electric field in NC^{- 1} of an electromagnetic wave is E = 36 π Sin (ω t - kx) . The average energy density of the electromagnetic wave due to the electric field is (\frac{1}{4 π ϵ _{o}} = 9 \times 10^{9} Nm^{2} C^{- 2})$ (1) $36 \times 10^{- 9} Jm^{- 3}$ (2) $18 \times 10^{- 9} Jm^{- 3}$ (3) $36 \times 10^{- 7} Jm^{- 3}$ (4) $18 \times 10^{- 7} Jm^{- 3}$ 33. $Red light differs from blue light as they have:$ (1) $Different frequencies and different wavelengths$ (2) $Different frequencies and same wavelengths$ (3) $Same frequencies and same wavelengths$ (4) $Same frequencies and different wavelengths$ 34. $A light of intensity 12 Wm^{- 2} incidents on a black surface of area 4 cm^{2} . The radiation pressure on the surface is$ (1) $1 \times 10^{- 8} Pa$ (2) $4 \times 10^{- 8} Pa$ (3) $1.6 \times 10^{- 7} Pa$ (4) $4.8 \times 10^{- 7} Pa$ 35. $The energy density associated with electric field E and magnetic field B of an electromagnetic wave in free space is given by (ε_{0} - permittivity of free space, μ_{0} - permeability of free space)$ (1) $U_{E} = \frac{E ^{2}}{2 ε _{0}}, U_{B} = \frac{B ^{2}}{2 μ _{0}}$ (2) $U_{E} = \frac{ε _{0} E ^{2}}{2}, U_{B} = \frac{B ^{2}}{2 μ _{0}}$ (3) $U_{E} = \frac{ε _{0} E ^{2}}{2}, U_{B} = \frac{μ _{0} B ^{2}}{2}$ (4) $U_{E} = \frac{E ^{2}}{2 ε _{0}}, U_{B} = \frac{μ _{0} B ^{2}}{2}$ 36. $The magnetic field of an electromagnetic wave is given by: B = 1.6 \times 10^{- 6} cos (2 \times 10^{7} z + 6 \times 10^{15} t) (2 i + j) \frac{Wb}{m ^{2}} The associated electric field will be:$ (1) $E = 4.8 \times 1 0^{2} cos [2 \times 1 0^{7} z - 6 \times 1 0^{15} t] (2 i + j) V / m$ (2) $E = 4.8 \times 1 0^{2} cos [2 \times 1 0^{7} z - 6 \times 1 0^{15} t] (- 2 j + i) V / m$ (3) $E = 4.8 \times 1 0^{2} cos [2 \times 1 0^{7} z + 6 \times 1 0^{15} t] (- i + 2 j) V / m$ (4) $E = 4.8 \times 1 0^{2} cos [2 \times 1 0^{7} z + 6 \times 1 0^{15} t] (i - 2 j) V / m$ 37. $A light wave is incident normally on a glass slab of refractive index If of light gets reflected and the amplitude of the electric field of the incident light is then the amplitude of the electric field for the wave propogating in the glass medium will be:$ (1) $30 V / m$ (2) $10 V / m$ (3) $24 V / m$ (4) $6 V / m$ 38. $Young's double slit experiment is first performed in air and then in a medium other than air. It is found that bright fringe in the medium lies where dark fringe lies in air. The refractive index of the medium is nearly:$ (1) $1.25$ (2) $1.59$ (3) $1.69$ (4) $1.78$ 39. $Light is incident normally on a completely absorbing surface with an energy flux of 25 W cm^{- 2} . If the surface has an area of 25 cm^{2}, the momentum transferred to the surface in 40 min time duration will be:$ (1) $6.3 \times 10^{- 4} Ns$ (2) $1.4 \times 10^{- 6} Ns$ (3) $5.0 \times 10^{- 3} Ns$ (4) $3.5 \times 10^{- 6} Ns$ 40. $The amplitude of electric field in an electromagnetic wave is 60 Vm^{- 1} . Then the amplitude of magnetic field is$ (1) $2 \times 10^{- 7} T$ (2) $2 \times 10^{7} T$ (3) $6 \times 10^{7} T$ (4) $6 \times 10^{- 7} T$ 41. $The energy of an electromagnetic wave contained in a small volume oscillates with$ (1) $Double the frequency of the wave$ (2) $The frequency of the wave$ (3) $Halt the frequency of the wave$ (4) $Zero frequency$ 42. $Due to presence of an em-wave whose electric component is given by E = 100 sin (ω t k x) NC^{- 1}, a cylinder of length 200 cm holds certain amount of em-energy inside it. If another cylinder of same length but half diameter than previous one holds same amount of em-energy, the magnitude of the electric field of the corresponding em-wave should be modified as$ (1) $400 sin (ω t - kx) NC^{- 1}$ (2) $200 sin (ωt - kx) NC^{- 1}$ (3) $50 sin (ωt - kx) NC^{- 1}$ (4) $25 sin (ωt - kx) NC^{- 1}$ 43. $The energy of the EM waves is of the order of 15 keV. To which part of the spectrum does it belong?$ (1) $X-rays$ (2) $Infrared rays$ (3) $Ultraviolet rays$ (4) $γ-rays$ 44. $Given below are two statements: Statement I: A time varying electric field is a source of changing magnetic field and vice-versa. Thus a disturbance in electric or magnetic field creates EM waves. Statement II: In a material medium. The EM wave travels with speed v = \frac{1}{μ _{0} ϵ _{0}} In the light of the above statements, choose the correct answer from the options given below:$ (1) $Both statement I and statement II are true.$ (2) $Both statement I and statement II are false.$ (3) $Statement I is correct but statement II is false.$ (4) $Statement I is incorrect but statement II is true.$ 45. $Match List - I with List - II. List. List I (A) Source of microwave frequency (B) Source of infrared frequency (C) Source of Gamma Rays (D) Source of X-rays List II (I) Radioactive decay of nucleus (II) Magnetron (III) Inner shell electrons (IV) Vibration of atoms and molecules (V) LASER (Vi) RC circuit Choose the correct answer from the options given below:$ (1) $(A) - (II), (B) - (IV), (C) - (I), (D) - (III)$ (2) $(A) - (VI), (B) - (IV), (C) - (I), (D) - (V)$ (3) $(A) - (II), (B) - (IV), (C) - (VI), (D) - (III)$ (4) $(A) - (VI), (B) - (V), (C) - (I), (D) - (IV)$ 46. $A parallel plate capacitor of capacitance 20 μF is being charged by a voltage source whose potential is changing at the rate of 3 V / s . The conduction current through the connecting wires, and the displacement current through the plates of the capacitor, would be, respectively$ (1) $zero, zero$ (2) $zero, 60 μA$ (3) $60 μA, 60 μA$ (4) $60 μA, zero$ 47. $The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to$ (1) $the speed of light in vacuum$ (2) $reciprocal of speed of light in vacuum$ (3) $the ratio of magnetic permeability to the electric susceptibility of vacuum$ (4) $unity$ 48. $An unpolarised light beam strikes a glass surface at Brewster's angle, then [NEET 2024]$ (1) $the reflected light will be partially polarized$ (2) $the refracted light will be completely polarised$ (3) $both the reflected and refracted light will be completely polarised$ (4) $the reflected light will be completely polarised but the refracted light will be partially polarised$ 49. $If the monochromatic source in Young's double slit experiment is replaced by white light, then [NEET 2024]$ (1) $interference pattern will disappear$ (2) $there will be a central dark fringe surrounded by a few coloured fringes$ (3) $there will be a central bright white fringe surrounded by a few coloured fringes$ (4) $all bright fringes will be of equal width$ 50. $For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E) and magnetic field (B), respectively? [NEET 2021]$ (1) $j + k, j + k$ (2) $- j + k, - j - k$ (3) $j + k, - j + k$ (4) $- j + k, - j + k$ 51. $The electric fields of two plane electromagnetic plane waves in vacuum are given by E \to_{1} = E_{o} j^cos (ωt - kx) E \to_{2} = E_{o} k^cos (ωt - ky) At t = 0, a particle of charge q is at origin with a velocity v \to= 0.8 c j^is the speed of the light in vacuum). The instantaneous force experienced by the particle is:$ (1) $q E_{0} (0.4 i^+ 0.2 j^+ 0.2 k^)$ (2) $q E_{0} (0.8 i^+ j^+ 0.2 k^)$ (3) $q E_{0} (0.6 i^+ j^+ 0.2 k^)$ (4) $q E_{0} (0.8 i^+ j^+ k^)$ 52. $If the magnetic field of a plane electromagnetic wave is given by 5 \times 10^{- 6} sin (0.6 \times 10^{2} x + 0.5 \times 10^{10} t), then the speed of the wave is$ (1) $0.83 \times 10^{7} m / s$ (2) $0.83 \times 10^{8} m / s$ (3) $5.24 \times 10^{8} m / s$ (4) $5.24 \times 10^{9} m / s$ 53. $A laser beam has intensity of 4.0 \times 10^{14} W / m^{2} . The amplitude of magnetic field associated with beam is____Т. (Take ϵ_{o} = 8.85 \times 10^{- 12} C^{2} / Nm^{2} and c = 3 \times 10^{8} m / s)$ (1) $18.3$ (2) $1.83$ (3) $5.5$ (4) $2.0$ 54. $Which of the following are true? (A) Speed of light in vacuum is dependent on the direction of propagation. (B) Speed of light in a medium in independent of the wavelength of light. (C) The speed of light is independent of the motion of the source. (D) The speed of light in a medium is independent of intensity. Choose the correct answer from the option given below:$ (1) $A and C only$ (2) $B and D only$ (3) $B and C only$ (4) $C and D only$ 55. $The electric fields of two plane electromagnetic plane waves in vacuum are given by : E_{1} = E_{0} j^cos(ωt - kx) and E_{2} = E_{0} k^cos(ωt - ky) At t = 0, a particle of charge q is at origin with a velocity v = 0.8 c j^(c is the speed of the light in vaccum). The instantaneous force experienced by the particle is :$ (1) $E_{0} q (0.8 i^+ j^+ 0.2 k^)$ (2) $E_{0} q (- 0.8 i^+ j^+ k^)$ (3) $E_{0} q (0.4 i^- 3 j^+ 0.8 k^)$ (4) $E_{0} q (0.8 i^- j^+ 0.4 k^)$ 56. $If E and B are the electric and magnetic field vectors of an electromagnetic wave, then the direction of propagation of the electromagnetic wave is$ (1) $along the direction of E$ (2) $along the direction of B$ (3) $parallel to the direction of E \times B$ (4) $perpendicular to the direction of E \times B$ 57. $Match the LIST-I with LIST-II List-I (A) Radio-wave (B) Micro-wave (C) Infrared-wave (D) X-ray List-II (I) is produced by Magnetron valve (II) due to change in the vibrational modes of atoms (III) due to inner shell electrons moving from higher to lower energy level (IV) due to rapid acceleration of electrons Choose the correct answer from the options given below:$ (1) $A-IV, B-II, C-I, D-III$ (2) $A-IV, B-I, C-II, D-III$ (3) $A-IV, B-III, C-I, D-II$ (4) $A-II, B-IV, C-III, D-I$ 58. $The magnetic field of a plane electromagnetic wave is given by: B = B_{0} i (cos (kz - ωt)) + B_{1} j cos (kx + ωt) Where B_{0} = 3 \times 10^{- 5} T and B_{1} = 2 \times 10^{- 6} T The rms value of the force experienced by a stationary charge Q = 10^{- 4} C at z = 0 is closest to:$ (1) $0.6 N$ (2) $0.1 N$ (3) $0.9 N$ (4) $3 \times 10^{- 2} N$ 59. $In a double slit experiment, the two slits are 1mm apart and the screen is placed 1 m away. A monochromatic light of wavelength 500 nm is used. What will be the width of each slit for obtaining ten maxima of double slit within the central maxima of single slit pattern?$ (1) $0.1 mm$ (2) $0.5 mm$ (3) $0.02 mm$ (4) $0.2 mm$ 60. $Given below are two statements: Statement I: Out of microwaves, infrared rays and ultraviolet rays, ultraviolet rays are the most effective for the emission of electrons from a metallic surface Statement II: Above the threshold frequency, the maximum kinetic energy of photoelectrons is inversely proportional to the frequency of the incident light In the light of above statements, choose the correct answer from the options given below$ (1) $Statement I is false but Statement II is true$ (2) $Statement I is true but Statement II is false$ (3) $Both Statement I and Statement II are true$ (4) $Both Statement I and Statement II are false$