Electromagnetic Waves PYQs Set 5 (PDF)

Set 5 of 9 · Questions 121-150 of 244

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Mere Teacher · Previous Year Questions NEET Physics · Electromagnetic Waves · Set 5 (Q121-150)
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121. $Which of the following radiation of electromagnetic waves has the highest wavelength?$ (1) $IR-rays$ (2) $X-rays$ (3) $Microwaves$ (4) $UV-rays$ 122. $The electric field (E) and magnetic field (B) of an electromagnetic wave passing through vacuum are given by E = E_{0} sin (kx - ωt) B = B_{0} sin (kx - ω t) Then the correct statement among the following is$ (1) $E_{0} k = B_{0} ω$ (2) $E_{0} ω = B_{0} k$ (3) $E_{0} B_{0} = ω k$ (4) $E_{0} B_{0} = \frac{ω}{k}$ 123. $Which is the correct ascending order of wavelengths?$ (1) $λ_{visible} < λ_{X - ray} < λ_{gamma - ray} < λ_{microwave}$ (2) $λ_{gamma - ray} < λ_{X - ray} < λ_{visible} < λ_{microwave}$ (3) $λ_{X - ray} < λ_{gamma - ray} < λ_{visible} < λ_{microwave}$ (4) $λ_{microwave} < λ_{visible} < λ_{gamma - ray} < λ_{X - ray}$ 124. $An electromagnetic wave in vacuum has the electric and magnetic field E and B, which are always perpendicular to each other. The direction of polarization is given by X and that of wave propagation by k . Then$ (1) $X ∣∣ B and k ∣∣ B \times E$ (2) $X ∣∣ E and k ∣∣ E \times B$ (3) $X ∣∣ B and k ∣∣ E \times B$ (4) $X ∣∣ E and k ∣∣ B \times E$ 125. $Given below are two statements: Statement I: Electromagnetic waves carry energy as they travel through space and this energy is equally shared by the electric and magnetic fields. Statement II: When electromagnetic waves strike a surface, a pressure is exerted on the surface. In the light of the above statements, choose the most appropriate answer from the options given below:$ (1) $Statement I is incorrect but Statement II is correct$ (2) $Both Statement I and Statement II are correct.$ (3) $Both Statement I and Statement II are incorrect.$ (4) $Statement I is correct but Statement II is incorrect.$ 126. $For the plane electromagnetic wave given by E = E_{0} sin (ωt - kx) and B = B_{0} sin (ωt - kx), the ratio of average electric energy density to average magnetic energy density is$ (1) $\frac{1}{2}$ (2) $2$ (3) $4$ (4) $1$ 127. $The ratio of resolving powers of an optical microscope for two wavelengths λ_{1} = 4000 Å and λ_{2} = 6000 Å is$ (1) $8 : 27$ (2) $9 : 4$ (3) $3 : 2$ (4) $16 : 81$ 128. $In Young's double slit experiment the separation d between the slits is 2 mm, the wavelength λ of the light used is 5896Å and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20^{\circ} . To increase the fringe angular width to 0.21^{\circ} (with same λ and D) the separation between the slits needs to be changed to [NEET 2018]$ (1) $1.8 mm$ (2) $1.9 mm$ (3) $2.1 mm$ (4) $1.7 mm$ 129. $In a double slit experiment, when light of wavelength 400 nm was used, the angular width of the first minima formed on a screen placed 1 m away, was found to be 0.2^{\circ} . What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? (μ_{water} = 4/3) [NEET 2019]$ (1) $0.15^{\circ}$ (2) $0.051^{\circ}$ (3) $0.1^{\circ}$ (4) $0.266^{\circ}$ 130. $50 W / m^{2} energy density of sunlight is normally incident on the surface of a solar panel. Some part of incident energy (25 %) is reflected from the surface and the rest is absorbed. The force exerted on 1 m^{2} surface area will be close to (c = 3 \times 10^{8} m / s)$ (1) $15 \times 10^{- 8} N$ (2) $20 \times 10^{- 8} N$ (3) $10 \times 10^{- 8} N$ (4) $35 \times 10^{- 8} N$ 131. $An electromagnetic wave is propagating in vacuum along - ȷ direction. The magnetic field of the wave is given by B = (2 \times 10^{- 8}) cos (π \times 10^{15} (t + \frac{y}{c})) k T . The electric field E of this wave is (c \equiv speed of light)$ (1) $E = (4) cos (π \times 10^{15} (t + \frac{y}{c})) j V / m$ (2) $E = (6) cos (π \times 10^{15} (t + \frac{y}{c})) iV / m$ (3) $E = (6) cos (π \times 10^{15} (t - \frac{y}{c})) j V / m$ (4) $E = (4) cos (π \times 10^{15} (t - \frac{y}{c})) iV / m$ 132. $If E and B represent electric and magnetic fidd vectors of an electromagnetic wave, the direction of propagation of the wave is along$ (1) $B \times E$ (2) $B$ (3) $E$ (4) $E \times B$ 133. $At an instant, a plane electromagnetic wave has its magnetic field in the direction of the vector i - j and its electric field is in the direction of i + j . The wave is travelling along which direction?$ (1) $+ x -direction$ (2) $- x -direction$ (3) $+ z -direction$ (4) $-z-direction$ 134. $A parallel beam of monochromatic light of frequency v is incident on a surface. The intensity of the beam is I and area of the surface is A . Find the force exerted by the light of beam on the surface is perfectly reflecting and the light beam is incident at an angle of incidence θ . (The speed of light is denoted as c)$ (1) $\frac{2 IA sin ^{2} θ}{πc}$ (2) $\frac{IA cos ^{2} θ}{c}$ (3) $\frac{2 IA cos ^{2} θ}{c}$ (4) $\frac{IA cos ^{2} θ}{2 c}$ 135. $Young's double slit experiment is first performed in air and then in a medium other than air. It is found that 8th bright fringe in the medium lies where 5th dark fringe lies in air. The refractive index of the medium is nearly [NEET 2017]$ (1) $1.25$ (2) $1.59$ (3) $1.69$ (4) $1.78$ 136. $A capacitor of capacitance C, is connected across an AC source of voltage V, given by V = V_{0} sinωt . The displacement current between the plates of the capacitor, would then be given by [NEET 2021]$ (1) $I_{d} = V_{0} ωCcosωt$ (2) $I_{d} = \frac{V _{0}}{ωC} cosωt$ (3) $I_{d} = \frac{V _{0}}{ωC} sinωt$ (4) $I_{d} = V_{0} ωCsinωt$ 137. $Light with an average flux of 20 W / cm^{2} falls on a non-reflecting surface at normal incidence having surface area 20 cm^{2} . The energy received by the surface during time span of 1 min is [NEET 2020]$ (1) $12 \times 10^{3} J$ (2) $24 \times 10^{3} J$ (3) $48 \times 10^{3} J$ (4) $10 \times 10^{3} J$ 138. $The condition under which a microwave oven heats up a food item containing water molecules most efficiently is$ (1) $Microwaves are heat waves, so always produce heating.$ (2) $Infra‐red waves produce heating in a microwave oven.$ (3) $The frequency of the microwaves must match the resonant frequency of the water molecules.$ (4) $The frequency of the microwaves has no relation with natural frequency of water molecules.$ 139. $A plane electromagnetic wave of frequency 50 MHz travels in free space along the positive x -direction. At a particular point in space and time, E = 6.3 j V / m . The corresponding magnetic field B \to, at that point will be:$ (1) $18.9 \times 10^{- 8} k T$ (2) $2.1 \times 10^{- 8} k T$ (3) $6.3 \times 10^{- 8} k T$ (4) $18.9 \times 10^{8} k T$ 140. $Out of the following options which one can be used to produce a propagating electromagnetic wave? [NEET 2019]$ (1) $A stationary charge$ (2) $A chargeless particle$ (3) $An accelerating charge$ (4) $A charge moving at constant velocity$ 141. $If a plane electromagnetic wave has electric field oscillations of frequency 3 GHz then the wavelength of the wave is (speed of light in vacuum = 3 \times 10^{8} ms^{- 1})$ (1) $0.1 m$ (2) $0.2 m$ (3) $100 m$ (4) $0.003 m$ 142. $The correct statement among the following is$ (1) $Electromagnetic waves cannot travel in vacuum$ (2) $Electromagnetic waves are longitudinal waves$ (3) $Electromagnetic waves are produced by charges moving with uniform velocity$ (4) $Electromagnetic waves carry both energy and momentum as they propagate through space.$ 143. $Intensity of sunlight is observed as 0.092 W m^{- 2} at a point in free space. What will be the peak value of magnetic field at that point? (ϵ_{0} = 8.85 \times 1 0^{- 12} C^{2} N^{- 1} m^{- 2})$ (1) $2.77 \times 1 0^{- 8} T$ (2) $1.96 \times 1 0^{- 8} T$ (3) $8.31T$ (4) $5.88T$ 144. $For an electromagnetic wave travelling in free space, the relation between average energy densities due to electric (U_{e}) and magnetic (U_{m}) fields is:$ (1) $U_{e} = U_{m}$ (2) $U_{e} > U_{m}$ (3) $U_{e} < U_{m}$ (4) $U_{e} \neq = U_{m}$ 145. $In a Young's double slit experiment, a student observes 8 fringes in a certain segment of screen when a monochromatic light of 600 nm wavelength is used. If the wavelength of light is changed to 400 nm, then the number of fringes he would observe in the same region of the screen is [NEET 2022]$ (1) $8$ (2) $9$ (3) $12$ (4) $6$ 146. $The unit of \frac{2 I}{ϵ _{0} c} is: (I = intensity of an electromagnetic wave, c = speed of light)$ (1) $Vm$ (2) $NC^{- 1}$ (3) $NC$ (4) $Nm$ 147. $In a plane electromagnetic wave, the maximum value of the electric field component is 4.4 Vm^{- 1} . The intensity of the wave is nearly$ (1) $22.4 mW m^{- 2}$ (2) $25.7 mW m^{- 2}$ (3) $65.5 mW m^{- 2}$ (4) $45.6 mW m^{- 2}$ 148. $The speed of electromagnetic waves in a medium is 1.5 \times 10^{8} ms^{- 1} . If relative permittivity of that medium is 2 , then its magnetic susceptibility is (speed of light in vacuum is 3 \times 10^{8} ms^{- 1}).$ (1) $2$ (2) $3$ (3) $1$ (4) $-1.5$ 149. $In a diffraction pattern due to a single slit of width , the first minimum is observed at an angle when light of wavelength is incident on the slit. The first secondary maximum is observed at an angle of [NEET 2016]$ (1) $sin^{- 1} (\frac{2}{3})$ (2) $sin^{- 1} (\frac{1}{2})$ (3) $sin^{- 1} (\frac{3}{4})$ (4) $sin^{- 1} (\frac{1}{4})$ 150. $If E and K represent electric field and propagation vectors of the EM waves in vacuum, then magnetic field vector is given by: (ω -angular frequency):$ (1) $\frac{1}{ω} (K \times E)$ (2) $ω (E \times K)$ (3) $ω K \times E$ (4) $K \times E$