Electromagnetic Waves PYQs Set 4 (PDF)

Set 4 of 9 · Questions 91-120 of 253

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Mere Teacher · Previous Year Questions JEE Main Physics · Electromagnetic Waves · Set 4 (Q91-120)
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91. $Which of the following statement is false for the properties of electromagnetic waves?$ (1) $Both electric and magnetic field vectors attain the maxima and minima at the same place and same time.$ (2) $The energy in electromagnetic wave is divided equally between electric and magnetic vectors.$ (3) $Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of wave.$ (4) $These waves do not require any material medium for propagation$ 92. $An em wave is propagating in a medium with a velocity v = v i . The instantaneous oscillating electric field of this em wave is along + y axis. Then the direction of oscillating magnetic field of the em wave will be along [NEET 2018]$ (1) $- z direction$ (2) $+ z direction$ (3) $- y direction$ (4) $- x direction$ 93. $A plane electromagnetic wave of frequency 500 MHz is travelling in vacuum along y -direction. At a particularpoint in space and time, B = 8.0 \times 10^{- 8} z T . The value of electricfield at this point is: (speed of light = 3 \times 10^{8} ms^{- 1}) x, y, z are unit vectors along x, y and z direction.$ (1) $- 24 x V / m$ (2) $2.6 x V / m$ (3) $24 x V / m$ (4) $- 2.6 y V / m$ 94. $An electromagnetic wave of frequency 3.0 MHz passes from vacuum into a non-magnetic medium with permittivity, ϵ = 16 ϵ_{0} . Where ϵ_{0} is the free space permittivity. The change in wavelength is$ (1) $- 75 m$ (2) $+ 75 m$ (3) $- 50 m$ (4) $+ 50 m$ 95. $A plane electromagnetic wave of frequency 50 MHz travels in free space. If the average energy densities in the electric field and magnetic field are K_{E} and K_{B} respectively, then the correct option in the following is$ (1) $K_{E} = K_{B}$ (2) $K_{E} = K_{B} = 0$ (3) $K_{E} > K_{B}$ (4) $K_{E} < K_{B}$ 96. $Electromagnetic radiation of intensity 0.6 Wm^{- 2} is falling on a black surface. The radiation pressure on the surface is$ (1) $2 \times 10^{- 9} Nm^{- 2}$ (2) $3 \times 10^{- 9} Nm^{- 2}$ (3) $4 \times 10^{- 9} Nm^{- 2}$ (4) $6 \times 10^{- 9} Nm^{- 2}$ 97. $Which of the following statement does not hold good for thermal radiation?$ (1) $The wavelength changes when it travels from one medium to another.$ (2) $The frequency changes when it travels from one medium to another.$ (3) $The speed changes when it travels from one medium to another.$ (4) $They travel in straight line in a given medium.$ 98. $If a source is transmitting electromagnetic wave of frequency 8.2 \times 10^{6} Hz, then wavelength of the electromagnetic waves transmitted from the source will be$ (1) $36.5 m$ (2) $40.5 m$ (3) $42.3 m$ (4) $50.9 m$ 99. $For a transparent medium relative permeability and permittivity, μ_{r} and ϵ_{r} are 1.0 and 1.44 respectively. The velocity of light in this medium would be$ (1) $2.5 \times 1 0^{8} m / s$ (2) $3 \times 1 0^{8} m / s$ (3) $2.08 \times 1 0^{8} m / s$ (4) $4.32 \times 1 0^{8} m / s$ 100. $The waves emitted when a metal target is bombarded with high energy electrons are$ (1) $Microwaves$ (2) $Infrared rays$ (3) $X-rays$ (4) $Radio Waves$ 101. $The electric field in an electromagnetic wave is given by E = i 40 cos ω (t - z / c) NC^{- 1} . The magnetic field induction of this wave is (in SI unit) :$ (1) $B = k \frac{40}{C} cos ω (t - z / c)$ (2) $B = j 40 cos ω (t - z / c)$ (3) $B = i \frac{40}{C} cos ω (t - z / c)$ (4) $B = j \frac{40}{C} cos ω (t - z / c)$ 102. $Light with an energy flux of 25 \times 1 0^{4} W m^{- 2} falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 c m^{2}, the average force exerted on the surface is$ (1) $1.25 \times 1 0^{- 6} N$ (2) $2.50 \times 1 0^{- 6} N$ (3) $1.20 \times 1 0^{- 6} N$ (4) $3.0 \times 1 0^{- 6} N$ 103. $The electric field of a plane electromagnetic wave is given by E = E_{0} i cos (kz) cos (ωt) The corresponding magnetic field B \to is then given by:$ (1) $B = \frac{E _{0}}{C} j sin (kz) sin (ωt)$ (2) $B = \frac{E _{0}}{C} j sin (kz) cos (ωt)$ (3) $B = \frac{E _{0}}{C} j cos (kz) sin (ωt)$ (4) $B = \frac{E _{0}}{C} k sin (kz) cos (ωt)$ 104. $For a transparent medium relative permeability and permittivity, μ_{r} and ϵ_{r}, are 1.0 and 1.44 respectively. The velocity of light in this medium would be [NEET 2019]$ (1) $2.5 \times 10^{8} m / s$ (2) $3 \times 10^{8} m / s$ (3) $2.08 \times 10^{8} m / s$ (4) $4.32 \times 10^{8} m / s$ 105. $An electromagnetic wave has its electric and magnetic fields given by E (t) = E_{m} sin (kx - ω t) B (t) = B_{m} sin (kx - ω t) If the direction of E_{m} & B_{m} are in the direction of ı + j and ı - j respectively, the unit vector that gives the direction of propagation of the wave is$ (1) $- k$ (2) $k$ (3) $ı$ (4) $- ı$ 106. $The magnetic field in a plane electromagnetic wave is given by B_{y} = 2 \times 10^{- 7} sin (π \times 10^{3} x + 3 π \times 10^{11} t) T Calculate the wavelength. [NEET 2020]$ (1) $π \times 10^{3} m$ (2) $2 \times 10^{- 3} m$ (3) $2 \times 10^{3} m$ (4) $π \times 10^{- 3} m$ 107. $An electromagnetic wave of frequency 1 \times 10^{14} Hz is propagating along z -axis. The amplitude of electric field is 4 Vm^{- 1}, then energy density of the electric field will be (Permittivity of free space = 8.8 \times 10^{- 12} C^{2} N^{- 1} m^{- 2})$ (1) $35.2 \times 10^{- 13} Jm^{- 3}$ (2) $70.4 \times 10^{- 13} Jm^{- 3}$ (3) $70.4 \times 10^{- 12} Jm^{- 3}$ (4) $35.2 \times 10^{- 12} Jm^{- 3}$ 108. $The property which is not of an electromagnetic wave travelling in free space is that [NEET 2024]$ (1) $They are transverse in nature$ (2) $The energy density in electric field is equal to energy density in magnetic field$ (3) $They travel with a speed equal to \frac{1}{μ _{0} ϵ _{0}}$ (4) $They originate from charges moving with uniform speed$ 109. $The displacement current through the plates of a parallel plate capacitor of capacitance 30 μ F is 150 μ A . The capacitor is charged by a source of varying potential at the rate of$ (1) $3.5 Vs^{- 1}$ (2) $2 Vs^{- 1}$ (3) $5 Vs^{- 1}$ (4) $3 Vs^{- 1}$ 110. $A plane electromagnetic wave of frequency 20 MHz travels through a space along x direction. If the electric field vector at a certain point in space is 6 V m m^{- 1}, what is the magnetic field vector at that point?$ (1) $2 T$ (2) $2 \times 10^{- 8} T$ (3) $1 2 T$ (4) $12\times 1 0^{- 8}$ 111. $The frequency order for X ‐rays (A), γ ‐rays (B), UV rays(c) is$ (1) $B > A > C$ (2) $A > B > C$ (3) $C > B > A$ (4) $A > C > B .$ 112. $A plane electromagnetic wave of frequency 20 MHz travels in free space along the + x direction. At a particular point in space and time, the electric field vector of the wave is E_{y} = 9.3 Vm^{- 1} . Then, the magnetic field vector of the wave at that point is$ (1) $B_{z} = 6.2 \times 10^{- 8} T$ (2) $B_{z} = 3.1 \times 10^{- 8} T$ (3) $B_{z} = 1.55 \times 10^{- 8} T$ (4) $B_{z} = 9.3 \times 10^{- 8} T$ 113. $Which of the following radiations deflected by electric field?$ (1) $γ -rays$ (2) $X-rays$ (3) $α -particles$ (4) $neutrons$ 114. $In a plane electromagnetic wave travelling in free space, the electric field component oscillates sinusoidally at a frequency of 2.0 \times 10^{10} Hz and amplitude 48 Vm^{- 1} . Then, the amplitude of oscillating magnetic field is (Speed of light in free space = 3 \times 10^{8} ms^{- 1}) [NEET 2023]$ (1) $1.6 \times 10^{- 8} T$ (2) $1.6 \times 10^{- 7} T$ (3) $1.6 \times 10^{- 6} T$ (4) $1.6 \times 10^{- 9} T$ 115. $A light beam of intensity 20 W cm^{- 2} is incident normally on a perfectly reflecting surface of sides 25 cm \times 15 cm . The momentum imparted to the surface by the light per second is$ (1) $5 \times 10^{- 5} kg m s^{- 1}$ (2) $1.2\times 1 0^{- 5} kg m s-1$ (3) $2 \times 10^{- 5} kg m s^{- 1}$ (4) $1 \times 10^{- 5} kg m s^{- 1}$ 116. $Match Column-I with Column-II Column-I (Electromagnetic waves) A. AM radio waves B. Microwaves C. Infrared radiations D. X-rays Column-II (Wavelength) I. 10^{- 10} m II. 10^{2} m III. 10^{- 2} m IV. 10^{- 4} m Choose the correct answer from the options given below. [NEET 2022]$ (1) $A-IV, B-III, C-II, D-I$ (2) $A-III, B-II, C-I, D-IV$ (3) $A-III, B-IV, C-II, D-I$ (4) $A-II, B-III, C-IV, D-I$ 117. $All components of the electromagnetic spectrum in vacuum have the same$ (1) $energy$ (2) $velocity$ (3) $wavelength$ (4) $frequency.$ 118. $An electromagnetic wave of frequency 100 MHz propagates through a medium of conductivity, σ = 10 mho / m . The ratio of maximum conduction current density to maximum displacement current density is____. (Take) (\frac{1}{4 π ϵ _{o}} = 9 \times 10^{9} Nm^{2} / C^{2})$ 119. $The electric field of a plane electromagnetic wave, travelling in an unknown nonmagnetic medium is given by, E_{y} = 20 sin (3 \times 10^{6} x - 4.5 \times 10^{14} t) V / m (where x, t and other values have S.I. units). The dielectric constant of the medium is____(speed of light in free space is 3 \times 10^{8} m / s)$ 120. $The equation of the electric field of an electromagnetic wave propagating through free space is given by: E = 377 sin (6.27 \times 10^{3} t - 2.09 \times 10^{- 5} x) N / C The average power of the electromagnetic wave is (\frac{1}{α}) W / m^{2} . The value of α is____(Take \frac{μ _{0}}{ϵ _{o}} = 377 in SI units)$