Electromagnetic Waves PYQs Set 8 (PDF)

Set 8 of 9 · Questions 211-240 of 244

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Mere Teacher · Previous Year Questions NEET Physics · Electromagnetic Waves · Set 8 (Q211-240)
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211. $Match List - I with List - II. List - I Relation (A) \oint E \cdot dl = - \frac{d}{dt} \oint B \cdot da (B) \oint B \cdot dl = μ_{0} (I + ϵ_{0} \frac{d φ _{E}}{dt}) (C) \oint E \cdot da = \frac{1}{ϵ _{0}} \int_{V} ρ d v (D) \oint B \cdot dl = μ_{0} I List - II Law (I) Ampere’s circuital law (II) Faraday’s laws of electromagnetic induction (III) Ampere - Maxwell law (IV) Gauss’s law of electrostatics Choose the correct answer from the options given below :$ (1) $A-II, B-III, C-I, D-IV$ (2) $A-II, B-III, C-IV, D-I$ (3) $A-I, B-IV, C-III, D-II$ (4) $A-IV, B-I, C-II, D-III$ 212. $Microwaves are used in$ (1) $TV$ (2) $radio transmission$ (3) $Radar$ (4) $atmospheric research$ 213. $The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is :$ (1) $3 V/m$ (2) $6 V/m$ (3) $9 V/m$ (4) $12 V/m$ 214. $For an EM wave, the electric and magnetic fields are 300 V / m and 7.9 A / m, respectively. The maximum rate of energy flow is$ (1) $2730 \frac{W}{m ^{2}}$ (2) $2790 \frac{W}{m ^{2}}$ (3) $2370 \frac{W}{m ^{2}}$ (4) $2390 \frac{W}{m ^{2}}$ 215. $In an electromagnetic wave the electric field vector and magnetic field vector are given as E = E_{0} i and B = B_{0} k respectively. The direction of propagation of electromagnetic wave is along:$ (1) $(k)$ (2) $(j)$ (3) $(- k)$ (4) $(- j)$ 216. $Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Electromagnetic waves carry energy but not momentum. Reason (R): Mass of a photon is zero. choose the most appropriate answer from the options given below:$ (1) $Both (A) and (R) are true and (R) is the correct explanation of (A)$ (2) $Both (A) and (R) are true but (R) is not the correct explanation of (A)$ (3) $(A) is false but (R) is true$ (4) $(A) is true but (R) is false$ 217. $Arrange the following in the ascending order of wavelength: A. Gamma rays (λ_{1}) B. x - rays (λ_{2}) C. Infrared waves (λ_{3}) D. Microwaves (λ_{4}) Choose the most appropriate answer from the options given below$ (1) $λ_{4} < λ_{3} < λ_{1} < λ_{2}$ (2) $λ_{2} < λ_{1} < λ_{4} < λ_{3}$ (3) $λ_{1} < λ_{2} < λ_{3} < λ_{4}$ (4) $λ_{4} < λ_{3} < λ_{2} < λ_{1}$ 218. $The energy associated with electric field is (U_{E}) and with magnetic field is (U_{B}) for an electromagnetic wave in free space. Then :$ (1) $U_{E} < U_{B}$ (2) $U_{E} = \frac{U _{B}}{2}$ (3) $U_{E} > U_{B}$ (4) $U_{E} = U_{B}$ 219. $The device used to detect infrared radiations is$ (1) $tachometer$ (2) $bolometer$ (3) $photocell$ (4) $point contact diode$ 220. $The structure of solids is investigated by using$ (1) $cosmic rays$ (2) $X ‐rays$ (3) $γ ‐rays$ (4) $infra‐red radiations$ 221. $If μ_{0} is permeability of free space and ϵ_{0} is permittivity of free space, the speed of light in vacuum is given by$ (1) $\frac{1}{μ _{0} ϵ _{0}}$ (2) $\frac{ϵ _{0}}{μ _{0}}$ (3) $μ_{0} ϵ_{0}$ (4) $\frac{μ _{0}}{ϵ _{0}}$ 222. $Two masses m and \frac{m}{2} are connected at the two ends of a massless rigid rod of length l . The road is suspended by a thin wire of torsional constant k at the centre of mass of the rod-mass system (see figure). Because of torsional constant k, the restoring torque is τ = kθ for angular displacement θ . If the rod is rota ted by θ_{0} and released, the tension in it when it passes through its mean position will be:$ (1) $\frac{3 k θ _{0}^{2}}{l}$ (2) $\frac{2 k θ _{0}^{2}}{l}$ (3) $\frac{k θ _{0}^{2}}{l}$ (4) $\frac{k θ _{0}^{2}}{2 l}$ 223. $An electromagnetic wave is represented by the electric field E = E_{0} n sin [ωt + (6 y - 8 z)] Taking unit vectors in x, y and z directions to be i^, j^, k^, the direction of propagation s is:$ (1) $s = \frac{3 i - 4 j}{5}$ (2) $s = \frac{- 4 k + 3 j}{5}$ (3) $s = (\frac{- 3 j + 4 k}{5})$ (4) $s = \frac{3 j - 3 k}{5}$ 224. $Ozone layer blocks the radiations of wavelength$ (1) $more than 3\times 1 0^{- 7} m$ (2) $equal to 3\times 1 0^{- 7} m$ (3) $less than 3\times 1 0^{- 7} m$ (4) $all of these$ 225. $The process of regaining of information from carrier wave at the receiver is termed as$ (1) $demodulation$ (2) $modulation$ (3) $attenuation$ (4) $amplification$ 226. $The correct order of electromagnetic waves with increasing frequency is$ (1) $Infrared, x -rays, gamma rays$ (2) $Gamma rays, visible light, x -rays$ (3) $Visible light, infrared, ultraviolet$ (4) $Visible light, ultraviolet, infrared$ 227. $The electric field and magnetic field components of an electromagnetic wave going through vacuum is described by E_{x} = e0sin (kz - ω t) B_{y} = B0sin (kz - ω t) Then the correct relation between E_{0} and B0 is given by$ (1) $k E_{0} = ω B_{0}$ (2) $E_{0} B_{0} = ωk$ (3) $ω E_{0} = k B_{0}$ (4) $E_{0} = k B_{0}$ 228. $A plane electromagnetic wave propagates along the + x direction in free space. The components of the electric field, E and magnetic field, B vectors associated with the wave in Cartesian frame are$ (1) $E_{x}, B_{y}$ (2) $E_{y}, B_{z}$ (3) $E_{z}, B_{y}$ (4) $E_{y}, B_{x}$ 229. $A linearly polarized electromagnetic wave in vacuum is E = 3.1 cos [(1.8) z - (5.4 \times 1 0^{6}) t] i^N/C is incident normally on a perfectly reflecting wall at z = a. Choose the correct option$ (1) $The wavelength is 5.4m$ (2) $The frequency of electromagnetic wave is 54 \times 1 0^{4} Hz$ (3) $The transmitted wave will be 3.1 cos [(1.8) z - (5.4 \times 1 0^{6}) t] i^N/C$ (4) $The reflected wave will be 1 cos [(1.8) z - (5.4 \times 1 0^{6}) t] i^N/C$ 230. $Identify the correct statements from the following descriptions of various properties of electromagnetic waves. (A) In a plane electromagnetic wave electric field and magnetic field must be perpendicular to each other and direction of propagation of wave should be along electric field or magnetic field. (B) The energy in electromagnetic wave is divided equally between electric and magnetic fields. (C) Both electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of wave. (D) The electric field, magnetic field and direction of propagation of wave must be perpendicular to each other. (E) The ratio of amplitude of magnetic field to the amplitude of electric field is equal to speed of light. Choose the most appropriate answer from the options given below:$ (1) $D only$ (2) $B and D only$ (3) $B, C and E only$ (4) $A, B and E only$ 231. $In frequency modulated wave$ (1) $frequency varies with time$ (2) $both frequency and amplitude vary with time$ (3) $amplitude varies with time$ (4) $both frequency and amplitude are constant$ 232. $Biological importance of ozone layer is$ (1) $it stops ultraviolet rays$ (2) $ozone layer reduces green house effect$ (3) $ozone layer reflects radio waves$ (4) $ozone layer controls O_{2} / H_{2} ratio in atmosphere.$ 233. $Wavelength of light of frequency 100 Hz$ (1) $4 \times 1 0^{6} m$ (2) $3 \times 1 0^{6} m$ (3) $2 \times 1 0^{6} m$ (4) $5 \times 1 0^{- 5} m$ 234. $Match the List-I with List-II: List I (A) Microwaves (B) Gamma rays (C) Radio waves (D) X-rays List II (I) Radioactive decay of the nucleus (II) Rapid acceleration and deceleration of electron in aerials (III) Inner shell electrons (IV) Klystron valve Choose the correct answer from the options given below:$ (1) $A-I, B-II, C-III, D-IV$ (2) $A-IV, B-I, C-II, D-III$ (3) $A-I, B-III, C-IV, D-II$ (4) $A-IV, B-III, C-II, D-I$ 235. $Which of the following rays are not electromagnetic waves?$ (1) $X ‐rays$ (2) $γ ‐rays$ (3) $β ‐rays$ (4) $heat rays$ 236. $Mach List-I with List - II: List I (A) Ultraviolet rays (B) Microwaves (C) Infrared waves (D) X-rays List II (I) Study crystal structure (II) Greenhouse effect (III) Sterilizing waves surgical instrument (IV) Radar system Choose the correct answer from the options given below:$ (1) $(A) - (III), (B) - (IV), (C) - (II), (D) - (I)$ (2) $(A) - (III), (B) - (I), (C) - (II), (D) - (IV)$ (3) $(A) - (IV), (B) - (III), (C) - (II), (D) - (I)$ (4) $(A) - (III), (B) - (IV), (C) - (I), (D) - (II)$ 237. $Light of wavelength 1 nm belongs to the following class of waves$ (1) $Radio waves$ (2) $Micro waves$ (3) $x-rays$ (4) $Gamma rays$ 238. $Match List-I with List-II List I (A) Microwaves (B) UV rays (C) Infra-red rays (D) X-rays List II (I) Physiotherapy (II) Treatment of cancer (III) Lasik eye surgery (IV) Aircraft navigation Choose the correct answer from the option given below:$ (1) $A-II, B-IV, C-III, D-I$ (2) $A-IV, B-I, C-II, D-III$ (3) $A-IV, B-III, C-I, D-II$ (4) $A-III, B-II, C-I, D-IV$ 239. $In a plane electromagnetic wave, U_{E} and U_{B} are average energy densities of electric field and magnetic field respectively, then the correct option in the following is$ (1) $U_{E} = U_{B} 2$ (2) $U_{E} = 2 U_{B}$ (3) $U_{E} = U_{B}$ (4) $U_{E} \neq = U_{B}$ 240. $During the propagation of electromagnetic waves in a medium :$ (1) $Electric energy density is double of the magnetic energy density.$ (2) $Electric energy density is half of the magnetic energy density.$ (3) $Electric energy density is equal to the magnetic energy density.$ (4) $Both electric and magnetic energy densities are zero.$