STD 12 - Electromagnetic waves PYQs: JEE Mains Physics – Page 3

Showing 101–150 of 161 questions

101. 101. Match List\(-I\) with List\(-II.\)

     List\(-I\)	List\(-II\)
     \((a)\) \(10\, km\) height over earth's surface	\((i)\) Thermosphere
     \((b)\) \(70\, km\) height over earth's surface	\((ii)\) Mesosphere
     \((c)\) \(180\, km\) height over earth's surface	\((iii)\) Stratosphere
     \((d)\) \(270\, km\) height over earth's surface	\((iv)\) Troposphere

     2021 Medium
102. 102. Match List - \(I\) with List - \(II.\)

     List - \(I\)	List - \(II\)
     \((a)\) Source of microwave frequency	\((i)\) Radioactive decay on nucleus
     \((b)\) Source of infrared frequency	\((ii)\) Magnetron
     \((c)\) Source of Gamma Rays	\((iii)\) Inner shell electrons
     \((d)\) Source of \(X-\)rays	\((iv)\) Vibration of atoms and molecules
     	\((v)\) \(LASER\)
     	\((vi)\) \(RC\) circuit

     Choose the correct answer from the options given below : 2021 Medium
103. 103. Red light differs from blue light as they have : 2021 Medium
104. 104. Seawater at a frequency \(f =9 \times 10^{2} \,Hz ,\) has permittivity \(\varepsilon=80\, \varepsilon_{0}\) and resistivity \(\rho=0.25\, \Omega m.\) Imagine a parallel plate capacitor is immersed in seawater and is driven by an alternating voltage source \(V ( t )= V _{0} \sin (2 \pi ft ) .\) Then the conduction current density becomes \(10^{x}\) times the displacement current density after time \(t =\frac{1}{800} \,s\). The value of \(x\) is ......... .
     \(\left(\frac{1}{4 \pi \varepsilon_{0}}=9 \times 10^{9} Nm ^{2} C ^{-2}\right)\) 2021 Hard
105. 105. The electric field in a plane electromagnetic wave is given by \(\overrightarrow{{E}}=200 \cos \left[\left(\frac{0.5 \times 10^{3}}{{m}}\right) {x}-\left(1.5 \times 10^{11} \frac{{rad}}{{s}} \times {t}\right)\right] \frac{{V}}{{m}} \hat{{j}}\) If this wave falls normally on a perfectly reflecting surface having an area of \(100 \;{cm}^{2}\). If the radiation pressure exerted by the \(E.M.\) wave on the surface during a \(10\, minute\) exposure is \(\frac{{x}}{10^{9}} \frac{{N}}{{m}^{2}}\). Find the value of \({x}\). 2021 Hard
106. 106. The electric field in an electromagnetic wave is given by \({E}=\left(50\, {NC}^{-1}\right) \sin \omega({t}-{x} / {c})\) The energy contained in a cylinder of volume \({V}\) is \(5.5 \times 10^{-12} \, {J}\). The value of \({V}\) is \(......{cm}^{3}\) \(\left(\right.\) given \(\left.\in_{0}=8.8 \times 10^{-12} \,{C}^{2} {N}^{-1} {m}^{-2}\right)\) 2021 Hard
107. 107. The magnetic field vector of an electromagnetic wave is given by \({B}={B}_{o} \frac{\hat{{i}}+\hat{{j}}}{\sqrt{2}} \cos ({kz}-\omega {t})\); where \(\hat{i}, \hat{j}\) represents unit vector along \({x}\) and \({y}\)-axis respectively. At \(t=0\, {s}\), two electric charges \(q_{1}\) of \(4\, \pi\) coulomb and \({q}_{2}\) of \(2 \,\pi\) coulomb located at \(\left(0,0, \frac{\pi}{{k}}\right)\) and \(\left(0,0, \frac{3 \pi}{{k}}\right)\), respectively, have the same velocity of \(0.5 \,{c} \hat{{i}}\), (where \({c}\) is the velocity of light). The ratio of the force acting on charge \({q}_{1}\) to \({q}_{2}\) is :- 2021 Hard
108. 108. A particle of mass \(\mathrm{m}\) and charge \(\mathrm{q}\) has an initial velocity \(\overline{\mathrm{v}}=\mathrm{v}_{0} \hat{\mathrm{j}} .\) If an electric field \(\overrightarrow{\mathrm{E}}=\mathrm{E}_{0} \hat{\mathrm{i}}\) and magnetic field \(\overrightarrow{\mathrm{B}}=\mathrm{B}_{0} \hat{\mathrm{i}}\) act on the particle, its speed will double after a time: 2020 Medium
109. 109. A plane electromagnetic wave, has frequency of \(2.0 \times 10^{10}\, Hz\) and its energy density is \(1.02 \times 10^{-8}\, J / m ^{3}\) in vacuum. The amplitude of the magnetic field of the wave is close to\(....nT\) \(\left(\frac{1}{4 \pi \varepsilon_{0}}=9 \times 10^{\circ} \frac{ Nm ^{2}}{ C ^{2}}\right.\) and speed of \(1 ight\) \(\left.=3 \times 10^{8}\, ms ^{-1}\right)\) 2020 Hard
110. 110. A plane electromagnetic wave is propagating along the direction \(\frac{\hat{i}+\hat{j}}{\sqrt{2}},\) with its polarization along the direction \(\hat{\mathrm{k}}\). The correct form of the magnetic field of the wave would be (here \(\mathrm{B}_{0}\) is an appropriate constant) 2020 Medium
111. 111. A plane electromagnetic wave of frequency \(25\; \mathrm{GHz}\) is propagating in vacuum along the \(z-\)direction. At a particular point in space and time, the magnetic field is given by \(\overrightarrow{\mathrm{B}}=5 \times 10^{-8} \hat{\mathrm{j}}\; \mathrm{T}\). The corresponding electric field \(\overrightarrow{\mathrm{E}}\) is (speed of light  \(\mathrm{c}=3 \times 10^{8}\; \mathrm{ms}^{-1})\) 2020 Easy
112. 112. An electron is constrained to move along the \(y-\)axis with a speed of \(0.1\, c\) (c is the speed of light) in the presence of electromagnetic wave, whose electric field is \(\overrightarrow{ E }=30 \hat{ j } \sin \left(1.5 \times 10^{7} t -5 \times 10^{-2} x \right)\, V / m\) The maximum magnetic force experienced by the electron will be: (given \(c=3 \times 10^{8}\, ms ^{-1}\) and electron charge \(\left.=1.6 \times 10^{-19} C \right)\) 2020 Medium
113. 113. Choose the correct option relating wavelengths of differnet parts of electromagnetic wave spectrum 2020 Medium
114. 114. For a plane electromagnetic wave, the magnetic field at a point \(x\) and time \(t\) is \(\overrightarrow{ B }( x , t )=\left[1.2 \times 10^{-7} \sin \left(0.5 \times 10^{3} x +1.5 \times 10^{11} t \right) \hat{ k }\right] T\) The instantaneous electric field \(\overrightarrow{ E }\) corresponding to \(\overrightarrow{ B }\) is : (speed of light \(\left.c=3 \times 10^{8} ms ^{-1}\right)\) 2020 Medium
115. 115. If the magnetic field in a plane electromagnetic wave is given by \(\overrightarrow{\mathrm{B}}=3 \times 10^{-8} \sin \left(1.6 \times 10^{3} \mathrm{x}+48 \times 10^{10} \mathrm{t}\right) \hat{\mathrm{j}}\; \mathrm{T}\) then what will be expression for electric field? 2020 Easy
116. 116. In a plane electromagnetic wave, the directions of electric field and magnetic field are represented by \(\hat{ k }\) and \(2 \hat{ i }-2 \hat{ j },\) respectively What is the unit vector along direction of propagation of the wave. 2020 Medium
117. 117. Suppose that intensity of a laser is \(\left(\frac{315}{\pi}\right)\, W / m ^{2} .\) The \(rms\) electric field, in units of \(V / m\) associated with this source is close to the nearest integer is \(\left(\epsilon_{0}=8.86 \times 10^{-12} C ^{2} Nm ^{-2} ; c =3 \times 10^{8} ms ^{-1}\right)\) 2020 Medium
118. 118. The correct match between the entries in column \(I\) and column \(II\) are              \(I\)                         \((II)\) Radiation                     Wavelength \((a)\) Microwave          \((i)\) \(100 m\) \((b)\) Gamma rays      \((ii)\) \(10^{-15} m\) \((c)\) \(A.M.\) radio waves        \((iii)\) \(10^{-10} m\) \((d)\) \(X-\)rays             \((iv)\) \(10^{-3} m\) 2020 Medium
119. 119. The electric field of a plane electromagnetic wave is given by \(\overrightarrow{\mathrm{E}}=\mathrm{E}_{0} \frac{\hat{\mathrm{i}}+\hat{\mathrm{j}}}{\sqrt{2}} \cos (\mathrm{kz}+\omega \mathrm{t})\) At \(\mathrm{t}=0,\) a positively charged particle is at the point \((\mathrm{x}, \mathrm{y}, \mathrm{z})=\left(0,0, \frac{\pi}{\mathrm{k}}\right) .\) If its instantaneous velocity at \((t=0)\) is \(v_{0} \hat{\mathrm{k}},\) the force acting on it due to the wave is 2020 Hard
120. 120. The electric field of a plane electromagnetic wave is given by \(\overrightarrow{ E }= E _{0}(\hat{ x }+\hat{ y }) \sin ( kz -\omega t )\) Its magnetic field will be given by 2020 Medium
121. 121. The electric field of a plane electromagnetic wave propagating along the \(x\) direction in vacuum is \(\overrightarrow{ E }= E _{0} \hat{ j } \cos (\omega t - kx )\). The magnetic field \(\overrightarrow{ B },\) at the moment \(t =0\) is : 2020 Hard
122. 122. The electric fields of two plane electromagnetic plane waves in vacuum are given by \(\overrightarrow{\mathrm{E}}_{1}=\mathrm{E}_{0} \hat{\mathrm{j}} \cos (\omega \mathrm{t}-\mathrm{kx})\) and \(\overrightarrow{\mathrm{E}}_{2}=\mathrm{E}_{0} \hat{\mathrm{k}} \cos (\omega \mathrm{t}-\mathrm{ky})\) At \(t=0,\) a particle of charge \(q\) is at origin with a velocity \(\overrightarrow{\mathrm{v}}=0.8 \mathrm{c} \hat{\mathrm{j}}\) (\(c\) is the speed of light in vacuum). The instantaneous force experienced by the particle is  2020 Hard
123. 123. The magnetic field of a plane electromagnetic Wave is \(\overrightarrow{ B }=3 \times 10^{-8} \sin [200 \pi( y + ct )] \hat{ i }\, T\) Where \(c=3 \times 10^{8} \,ms ^{-1}\) is the speed of light. The corresponding electric field is 2020 Hard
124. 124. A \(27\, mW\) lager beam has a cross -sectional area of \(10\, mm^2\). The magnitude of the maximum electric field in this electromagnetic wave is given by:........\(kV/m\) [Given permittivity of space \({ \in _0} = 9 \times {10^{ - 12}}\, SI\, units\), speed of light \(c = 3 \times 10^8\, m/s\)] 2019 Medium
125. 125. A light wave is incident normally on a glass slab of refractive index \(1.5\). If \(4\%\) of light gets reflected and the amplitude of the electric field of the incident light is \(30\, V/m\), then the amplitude of the electric field for the wave propagating in the glass medium will be.......\( V/m\) 2019 Hard
126. 126. A plane electromagnetic wave having a frequency \(n = 23.9\, GHz\) propagates along the positive \(z-\) direction in free 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? 2019 Medium
127. 127. 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, \(\vec E = 6.3\,\hat j\,V/m\) . The corresponding magnetic field \(\vec B\), at that point will be 2019 Easy
128. 128. A plane electromagnetic wave travels in free space along the \(x -\) direction. The electric field component of the wave at a particular point of space and time is \(E =6\; Vm^{-1}\) along \(y -\) direction. Its corresponding magnetic filed component, \(B\) would be 2019 Medium
129. 129. An electromagnetic wave is represented by the electric field \(\vec E = {E_0}\hat n\,\sin \,\left[ {\omega t + \left( {6y - 8z} \right)} \right]\). Taking unit vectors in \(x, y\) and \(z\) directions to be \(\hat i,\hat j,\hat k\) ,the direction of propogation \(\hat s\), is 2019 Medium
130. 130. An electromagnetic wave of intensity \(50\,Wm^{-2}\) enters in a medium of refractive index \(’ n’\) without any loss . The ratio of the magnitudes of electric fields, and the ratio of the magnitudes of magnetic fields of the wave before and after entering into the medium are respectively. Given by 2019 Hard
131. 131. Given below in the left column are different modes of communication using the kinds of waves given in the right column

     \(A.\) Optical Fiber Communication	\(P.\) Ultrasound
     \(B.\) Radar	\(Q.\) Infrared Light
     \(C.\) Sonar	\(R.\) Microwaves
     \(D.\) Mobile Phones	\(S.\) Radio Waves

     From the options given below, find the most appropriate match between entries in the left and the right column 2019 Medium
132. 132. If the magnetic field of a plane electromagnetic wave is given by (The speed of light \( = 3 \times {10^8}\,m/s\) ) \(B = 100 \times {10^{ - 6}}\,\sin \,\left[ {2\pi  \times 2 \times {{10}^{15}}\,\left( {t - \frac{x}{c}} \right)} \right]\)  then the maximum electric field associated with it is 2019 Easy
133. 133. The electric field of a plane electromagnetic wave is given by \(\vec E = {E_0}\hat i\,\cos \,\left( {kz} \right)\,\cos \,\left( {\omega t} \right)\) The corresponding magnetic field \(\vec B\) is then given by 2019 Medium
134. 134. The energy associated with electric field is \((U_E)\) and with magnetic field is \((U_B)\) for an electromagnetic wave in free space. Then 2019 Medium
135. 135. The magnetic field of a plane electromagnetic wave is given by \(\vec B\, = {B_0}\hat i\,[\cos \,(kz - \omega t)]\, + \,{B_1}\hat j\,\cos \,(kz - \omega t)\) 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 closet to 2019 Hard
136. 136. The magnetic field of an electromagnetic wave is given by \(\vec B = 1.6 \times {10^{ - 6}}\,\cos \,\left( {2 \times {{10}^7}z + 6 \times {{10}^{15}}t} \right)\left( {2\hat i + \hat j} \right)\frac{{Wb}}{{{m^2}}}\) The associated electric field will be 2019 Medium
137. 137. The mean intensity of radiation on the surface of the Sun is about \(10^{8}\,W/m^2.\) The \(rms\) value of the corresponding magnetic field is closet to 2019 Medium
138. 138. A monochromatic beam of light has a frequency \(v = \frac{3}{{2\pi }} \times {10^{12}}\,Hz\) and is propagating along the direction \(\frac{{\hat i + \hat j}}{{\sqrt 2 }}\). It is polarized along the \(\hat k\) direction. The acceptable form for the magnetic field is 2018 Hard
139. 139. A plane electromagnetic wave of wavelength \(\lambda \) has an intensity \(I.\)  It is propagating along the positive \(Y-\)  direction. The allowed expressions for the electric and magnetic fields are given by 2018 Medium
140. 140. A plane polarized monochromatic \(EM\) wave is travelling a vacuum along \(z\) direction such that at \(t\, = t_1\) it is found that the electric field is zero at a spatial point \(z_1\) . The next zero that occurs in its neighbourhood is at \(z_2\). The frequency of the electromagnetic wave is: 2018 Hard
141. 141. An EM wave from air enters a medium. The electric fields are \(\overrightarrow {{E_1}}  = {E_{01}}\hat x\;cos\left[ {2\pi v\left( {\frac{z}{c} - t} \right)} \right]\) in air and \(\overrightarrow {{E_2}}  = {E_{02}}\hat x\;cos\left[ {k\left( {2z - ct} \right)} \right]\) in medium, where the wave number \(k\) and frequency \(v\) refer to their values in air. The medium is nonmagnetic. If \(\varepsilon {_{{r_1}}}\) and \(\varepsilon {_{{r_2}}}\) refer to relative permittivities of air and medium respectively, which of the following options is correct? 2018 Medium
142. 142. Magnetic field in a plane electromagnetic wave is given by  \(\vec B = {B_0}\,\sin \,\left( {kx + \omega t} \right)\hat jT\)  Expression for corresponding electric field will be Where \(c\) is speed of light 2017 Medium
143. 143. The electric field component of a monochromatic radiation is given by \(\vec E = 2{E_0}\,\hat i\,\cos\, kz\,\cos\, \omega t\) Its magnetic field \(\vec B\) is then given by 2017 Hard
144. 144. Arrange the following electromagnetic radiations per quantum in the order of increasing energy :- \(A\) : Blue light \(B\) : Yellow light \(C\) : X-ray \(D\) : Radiowave 2016 Medium
145. 145. Consider an electromagnetic wave propagating in vacuum . Choose the correct statement 2016 Medium
146. 146. 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....\( Vm^{-1}\) 2015 Medium
147. 147. An electromagnetic wave travelling in the \(x-\) direction has frequency of \(2 \times 10^{14}\,Hz\) and electric field amplitude of \(27\,Vm^{-1}\) . From the options given below, which one describes the magnetic field for this wave ? 2015 Medium
148. 148. For plan electromagnetic waves propagating in the \(z-\) direction, which one of the following combination gives the correct possible direction for \(\vec E\) and \(\vec B\) field respectively? 2015 Medium
149. 149. A lamp emits monochromatic green light uniformly in all directions. The lamp is \(3\%\) efficient in converting electrical power to electromagnetic waves and consumes \(100\,W\) of power . The amplitude of the electric field associated with the electromagnetic radiation at a distance of \(5\,m\) from the lamp will be nearly.......\(V/m\) 2014 Hard
150. 150. An electromagnetic wave of frequency \(1\times10^{14}\, hertz\) is propagating along \(z-\) axis. The amplitude of electric field is \(4\, V/m\) . lf \({\varepsilon_0}=\, 8.8\times10^{-12}\, C^2/Nm^2\) , then average energy density of electric field will be: 2014 Medium

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