Electromagnetic Waves PYQs Set 7 (PDF)

Set 7 of 9 · Questions 181-210 of 253

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Mere Teacher · Previous Year Questions JEE Main Physics · Electromagnetic Waves · Set 7 (Q181-210)
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181. $Electromagnetic wave consists of periodically oscillating electric and magnetic vectors$ (1) $in mutually perpendicular planes but vibrating with a phase difference of π$ (2) $in mutually perpendicular planes but vibrating with a phase difference of \frac{π}{2}$ (3) $in randomly oriented planes but vibrating in phase$ (4) $in mutually perpendicular planes but vibrating in phase.$ 182. $The magnetic field in a plane electromagnetic wave is B_{y} = (3.5 \times 10^{- 7}) sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) T . The corresponding electric field will be :$ (1) $E_{y} = 10.5 sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) Vm^{- 1}$ (2) $E_{z} = 1.17 sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) Vm^{- 1}$ (3) $E_{y} = 1.17 sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) Vm^{- 1}$ (4) $E_{z} = 105 sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) Vm^{- 1}$ 183. $The electromagnetic wave with shortest wavelength among the following is [NEET 2020]$ (1) $UV-rays$ (2) $X-rays$ (3) $γ-rays$ (4) $micro waves$ 184. $A plane electromagnetic wave having a frequency v = 23.9 GHz propagates along the positive z -direction infree space. The peak value of the Electric Field is 60 V / m Which among the following is the acceptable magnetic field component in the electromagnetic wave?$ (1) $B = 2 \times 10^{7} sin (0.5 \times 10^{3} z + 1.5 \times 10^{11} t) i$ (2) $B = 2 \times 1 0^{- 7} sin (0.5 \times 1 0^{3} z - 1.5 \times 1 0^{11} t) i^$ (3) $B = 60 sin (0.5 \times 10^{3} x + 1.5 \times 10^{11} t) k$ (4) $B = 2 \times 1 0^{- 7} sin (1.5 \times 1 0^{2} x + 0.5 \times 1 0^{11} t) j^$ 185. $The electric field of an electromagnetic wave travelling through a medium is given by then the refractive index of the medium is .(All given measurement are in SI units)$ (1) $1.5$ (2) $1.2$ (3) $1.7$ (4) $2$ 186. $If λ_{v}, λ_{x} and λ_{m} represent the wavelengths of visible light, X ‐rays and microwaves respectively, then$ (1) $λ_{m} > λ_{x} > λ_{v}$ (2) $λ_{m} > λ_{v} > λ_{x}$ (3) $λ_{v} > λ_{x} > λ_{m}$ (4) $λ_{v} > λ_{m} > λ_{x}$ 187. $An electromagnetic wave of frequency ν = 3.0 MHz passes from vacuum into a dielectric medium with relative permittivity ϵ = 4.0 . Then$ (1) $Wavelength is doubled and frequency becomes half.$ (2) $Wavelength is halved and frequency remains unchanged.$ (3) $Wavelength and frequency both remain unchanged.$ (4) $Wavelength is doubled and frequency unchanged$ 188. $A point source of electromagnetic radiation has an average power output of 960 W . The peak value of the electric field at a distance 400 cm from the source is$ (1) $60 Vm^{- 1}$ (2) $120 Vm^{- 1}$ (3) $30 Vm^{- 1}$ (4) $180 Vm^{- 1}$ 189. $A signal emitted by an antenna from a certain point can be received at another point of the surface in the form of$ (1) $sky wave$ (2) $ground wave$ (3) $sea wave$ (4) $both (a) and (b)$ 190. $Assume that, light of wavelength 600 nm is coming from a star. The limit of resolution of telescope whose objective has a diameter of 2 m is [NEET 2020]$ (1) $1.83 \times 10^{- 7} rad$ (2) $7.32 \times 10^{- 7} rad$ (3) $6.00 \times 10^{- 7} rad$ (4) $3.66 \times 10^{- 7} rad$ 191. $Given below are two statements: Statement I: Electromagnetic waves are not deflected by electric and magnetic field. Statement II: The amplitude of electric field and the magnetic field in electromagnetic waves are related to each other as E_{0} = \frac{μ _{0}}{ϵ _{0}} B0 In the light of the above statements, choose the correct answer from the options given below:$ (1) $Statement 1 is true but statement II is false$ (2) $Both Statement I and Statement II are true$ (3) $Statement 1 is false but statement II is true$ (4) $Both Statement I and Statement II are false$ 192. $Two polaroids P_{1} and P_{2} are placed with their axis perpendicular to each other. Unpolarised light I_{0} is incident on P_{1} . A third polaroid P_{3} is kept in between P_{1} and P_{2} such that its axis makes an angle 45^{\circ} with that of P_{1} . The intensity of transmitted light through P_{2} is [NEET 2017]$ (1) $\frac{I _{0}}{2}$ (2) $\frac{I _{0}}{4}$ (3) $\frac{I _{0}}{8}$ (4) $\frac{I _{0}}{16}$ 193. $For a parallel beam of monochromatic light of wavelength diffraction is produced by a single slit whose width is of the order of the wavelength of the light. If is the distance of the screen from the slit, the width of the central maxima will be$ (1) $\frac{2 Dλ}{a}$ (2) $\frac{Dλ}{a}$ (3) $\frac{Da}{λ}$ (4) $\frac{2 Da}{λ}$ 194. $The electric field of a plane polarized electromagnetic wave in free space at time t = 0 is given by an expression E (x, y) = 10 j cos [(6 x + 8 z)] The magnetic field B (x, z, t) is given by: (C is the velocity of light)$ (1) $\frac{1}{C} (6 k + 8 i) cos [6 x - 8 z + 10 c t]$ (2) $\frac{1}{C} (6 k - 8 i) cos [6 x + 8 z - 10 c t]$ (3) $\frac{1}{C} (6 k + 8 i) cos [(6 x + 8 z - 10 c t)]$ (4) $\frac{1}{C} (6 k - 8 i) cos [(6 x + 8 z + 10 c t)]$ 195. $If the magnetic field of a plane electromagnetic wave is given by (The speed of light = 3 \times 1 0^{8} m/s) B = 100 \times 1 0^{-6} sin [2 π \times 2 \times 1 0^{15} (t - \frac{x}{c})] then the maximum electric field associated with it is$ (1) $4.5\times 1 0^{4} N/C$ (2) $4\times 1 0^{4} N/C$ (3) $6\times 1 0^{4} N/C$ (4) $3 \times 1 0^{4} N/C$ 196. $A light ray falls on a glass surface of refractive index at an angle . The angle between the refracted and reflected rays would be [NEET 2022]$ (1) $60^{\circ}$ (2) $90^{\circ}$ (3) $120^{\circ}$ (4) $30^{\circ}$ 197. $Unpolarised light is incident from air on a plane surface of a material of refractive index . At a particular angle of incidence , it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation? [NEET 2018]$ (1) $i = sin^{- 1} (\frac{1}{μ})$ (2) $Reflected light is polarised with its electric vector perpendicular to the plane of incidence$ (3) $Reflected light is polarised with its electric vector parallel to the plane of incidence$ (4) $i = tan^{- 1} (\frac{1}{μ})$ 198. $Arrange the following electromagnetic radiations per quantum in the order of increasing energy : A : Blue light B : Yellow light C : X-ray D : Radiowave$ (1) $A, B, D, C$ (2) $C, A, B, D$ (3) $B, A, D, C$ (4) $D, B, A, C$ 199. $If the magnetic field in a plane electromagnetic wave is given by B = 3 \times 1 0^{- 8} sinT, then what will be expression for electric field?$ (1) $E = (3 \times 1 0^{- 8} sin (1.6 \times 1 0^{3} x + 48 \times 1 0^{10} t) j^V/m)$ (2) $E = (3 \times 1 0^{- 8} sin (1.6 \times 1 0^{3} x + 48 \times 1 0^{10} t) i^V/m)$ (3) $E = (60 sin (1.6 \times 1 0^{3} x + 48 \times 1 0^{10} t) k^V/m)$ (4) $E = (9 sin (1.6 \times 1 0^{3} x + 48 \times 1 0^{10} t) k^V/m)$ 200. $A plane electromagnetic wave of frequency 20 MHz propagates in free space along x-direction. At a particular space and time E = 6.6 j V m^{- 1} . What is B at this point?$ (1) $2.2 x 1 0^{- 8} k^T$ (2) $-2.2 x 1 0^{- 8} i^T$ (3) $-2.2 x 1 0^{- 8} k^T$ (4) $2.2 x 1 0^{- 8} i^T$ 201. $An electron enters the space between the plates of a charged capacitor as shown. The charge density on the plate is σ . Alectric intensity in the space between the plates is E. A uniform magnetic field B also exists in that space perpendicular to the direction of E . The electron moves perpendicular to both E and B without any change in direction. The time taken by the electron to travel a distance l in that space is$ (1) $\frac{σl}{ϵ _{0} B}$ (2) $\frac{σB}{ϵ _{0} l}$ (3) $\frac{ϵ _{0} lB}{σ}$ (4) $\frac{ϵ _{0} l}{σB}$ 202. $In an electromagnetic wave, at an instant and at a particular position, the electric field is along the negative z-axis and magnetic field is along the positive x-axis. Then the direction of propagation of electromagnetic wave is:$ (1) $positive z-axis$ (2) $positive y-axis$ (3) $at 45° angle from positive y-axis$ (4) $negative y-axis$ 203. $The velocity of electromagnetic wave is parallel to$ (1) $B \times E$ (2) $E \times B$ (3) $E$ (4) $B$ 204. $An electromagnetic wave is travelling in x -direction with electric field vector given by, E_{y} = E_{0} sin (kx - ωt) j . The correct expression for magnetic field vector is$ (1) $B_{y} = \frac{E _{0}}{C} sin (kx - ωt) j$ (2) $B_{y} = E_{0} C sin (kx - ωt) j$ (3) $B_{z} = \frac{E _{0}}{C} sin (kx - ωt) k$ (4) $B_{z} = E_{0} C sin (kx - ωt) k$ 205. $The intensity at the maximum in a Young's double slit experiment is I_{0} . Distance between two slits is d = 5 λ, where λ is the wavelength of light used in the experiment. What will be the intensity infront of one of the slits on the screen placed at a distance D = 10 d ? [NEET 2016]$ (1) $\frac{I _{0}}{4}$ (2) $\frac{3}{4} I_{0}$ (3) $\frac{I _{0}}{2}$ (4) $I_{0}$ 206. $Which of the following Maxwell's equation is valid for time varying conditions but not valid for static conditions:$ (1) (2) (3) (4) 207. $At the first minimum adjacent to the central maximum of a single slit diffraction pattern, the phase difference between the Huygens' wavelet from the edge of the slit and the wavelet from the mid-point of the slit is$ (1) $\frac{π}{4} radian$ (2) $\frac{π}{2} radian$ (3) $π radian$ (4) $\frac{π}{8} radian$ 208. $In a plane EM wave the electric field oscillates sinusoidally at a frequency of 30 MHz and amplitude 150 V/m. Identify the correct expression of B assuming the wave is propagating along x -axis and is oscillating along y -axis.$ (1) $5 \times 1 0^{- 7} sin [\frac{x}{3} - 6 \times 1 0^{+ 7} t] z^T$ (2) $5 \times 1 0^{- 7} sin [π (\frac{x}{5} - 6 \times 1 0^{+ 7} t)] z^T$ (3) $5 \times 1 0^{- 7} sin [π (\frac{x}{10} - 3 \times 1 0^{+ 7} t)] z^T$ (4) $5 \times 1 0^{- 7} sin [π (\frac{2 x}{5} - 6 \times 1 0^{+ 8} t)] z^T$ 209. $When light propagates through a material medium of relative permittivity ϵ_{r} and relative permeability μ_{r}, the velocity of light, v is given by ( c-velocity of light in vacuum) [NEET 2022]$ (1) $v = \frac{μ _{r}}{ϵ _{r}}$ (2) $v = \frac{ϵ _{r}}{μ _{r}}$ (3) $v = \frac{c}{ϵ _{r} μ _{r}}$ (4) $v = c$ 210. $A parallel plate capacitor of area A = 16 cm^{2} and separation between the plates 10 cm, is charged by a DC current. Consider a hypothetical plane surface of area A_{0} = 3.2 cm^{2} inside the capacitor and parallel to the plates. At an instant, the current through the circuit is 6 A. At the same instant the displacement current through A_{0} is mA.$