Dual Nature of Matter & Radiation PYQs Set 8 (PDF)

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Mere Teacher · Previous Year Questions NEET Physics · Dual Nature of Matter & Radiation · Set 8 (Q211-240)
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211. $What is the de Broglie wavelength of the electron accelerated through a potential difference of 100 volt?$ (1) $0.1227Å$ (2) $12.27Å$ (3) $0.001227Å$ (4) $1.227Å$ 212. $Electrons of mass m with de-Broglie wavelength λ fall on the target in an X-ray tube. The cut-off wavelength (λ_{0}) of the emitted X-ray is [NEET 2016]$ (1) $λ_{0} = \frac{2 mc λ ^{2}}{h}$ (2) $λ_{0} = \frac{2 h}{mc}$ (3) $λ_{0} = \frac{2 m ^{2} c ^{2} λ ^{3}}{h ^{2}}$ (4) $λ_{0} = λ$ 213. $Radiations of wavelength 400 nm incidents on a photo sensitive material of work function 2.2 eV . The stopping potential is nearly$ (1) $0.9 V$ (2) $0.5 V$ (3) $0.4 V$ (4) $0.1 V$ 214. $The number of photo electrons emitted for light of a frequency ν (higher than the threshold frequency ν_{0}) is proportional to$ (1) $threshold frequency (ν_{0})$ (2) $intensity of light$ (3) $frequency of light (ν)$ (4) $ν - ν_{0}$ 215. $The velocity of a particle A is 3 times the velocity of proton. If the ratio of the de Broglie wavelengths of the particle A and the proton is 3:2, the mass of the particle A is (m_{p} - mass of proton)$ (1) $\frac{2}{9} m_{p}$ (2) $\frac{2}{3} m_{p}$ (3) $\frac{2}{5} m_{p}$ (4) $\frac{2}{7} m_{p}$ 216. $An electron with speed v and a photon with speed c have the same de-Broglie wavelength. If the kinetic energy and momentum of electron are E_{e} and pe and that of photon are E_{p h} and p_{p h} respectively. Which of the following is correct?$ (1) $\frac{E _{e}}{E _{ph}} = \frac{2 c}{V}$ (2) $\frac{E _{e}}{E _{ph}} = \frac{v}{2 c}$ (3) $\frac{p _{e}}{p _{ph}} = \frac{2 c}{v}$ (4) $\frac{p _{e}}{p _{ph}} = \frac{v}{2 c}$ 217. $A proton moving with a momentum P_{1} has a kinetic energy (\frac{1}{8})^{th} of its rest mass energy. Another light photon having energy equal to the kinetic energy of the proton possesses a momentum P_{2} . Then the ratio \frac{P _{1} - P _{2}}{P _{1}} is equal to$ (1) $1$ (2) $\frac{1}{4}$ (3) $\frac{1}{2}$ (4) $\frac{3}{4}$ 218. $When photons of energies twice and thrice the work function of a metal incident on the meta! surface one after other, the maximum velocities of the photoelectrons emitted in the two cases are y_{1} and v_{2} respectively. The ratio v_{1} : v_{2} is$ (1) $2 : 1$ (2) $3 : 1$ (3) $3 : 2$ (4) $1 : 2$ 219. $The de‐Broglie wavelength of neutrons in thermal equilibrium at temperature T is$ (1) $\frac{3.08}{T} A ˚$ (2) $\frac{0.308}{T} A ˚$ (3) $\frac{0.0308}{T} A ˚$ (4) $\frac{30.8}{T} A ˚$ 220. $λ_{1} and λ_{2} are used to illuminate the slits. β_{1} and β_{2} are the corresponding fringe widths. The wavelength λ_{1} can produce photoelectric effect when incident on a metal. But the wavelength λ_{2} cannot produce photoelectric effect. The correct relation between β_{1} and β_{2} is$ (1) $β_{1} < β_{2}$ (2) $β_{1} = β_{2}$ (3) $β_{1} > β_{2}$ (4) $β_{1} \geq β_{2}$ 221. $A 200 W sodium street lamp emits yellow light of wavelength 0.6 μm . Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is$ (1) $1.5 \times 1 0^{20}$ (2) $6 \times 1 0^{18}$ (3) $62 \times 1 0^{20}$ (4) $3 \times 1 0^{19}$ 222. $In a photoelectric experiment light of wavelength 800 nm produces photoelectrons with the smallest de-Broglie wavelength of 1 nm . Light of 400 nm produces photoelectrons with smallest de-Broglie wavelength of 0.5 nm . Then the work function of the metal used in the experiment is nearly$ (1) $1.03 eV$ (2) $0.53 eV$ (3) $2.03 eV$ (4) $4.02 eV$ 223. $The maximum kinetic energy of emitted photoelectrons depends on$ (1) $intensity of incident radiation$ (2) $frequency of incident radiation$ (3) $speed of incident radiation$ (4) $number of photons in the incident rotation.$ 224. $A metal exposed to light of wavelength 800 nm and emits photoelectrons with a certain kinetic energy. The maximum kinetic energy of photo-electron doubles when light of wavelength 500 nm is used. The work function of the metal is (Take he = 1230 eV-nm).$ (1) $1.537eV$ (2) $2.46 eV$ (3) $0.615eV$ (4) $1.23 eV$ 225. $All electrons ejected from a metallic surface by incident light of wavelength 400 nm travelled 1 m in the direction of uniform electric field of 2 NC^{- 1} and came to rest. The work function of the surface is$ (1) $1.1 eV$ (2) $2.2 eV$ (3) $3.1 eV$ (4) $5.1 eV$ 226. $Given below are two statements: Statement-I: Stopping potential in photoelectric effect does not depend on the power of the light source. Statement-II: For a given metal, the maximum kinetic energy of the photoelectron depends on the wavelength of the incident light. In the light of above statements, choose the most appropriate answer from the options given below.$ (1) $Statement I is incorrect but statement II is correct$ (2) $Both Statement I and Statement II are incorrect$ (3) $Statement I is correct but statement II is incorrect$ (4) $Both statement I and statement II are correct$ 227. $A proton, a neutron, an electron and an α -particle have same energy. If λ p, λ n, λ e and λ_{α} are the de Broglie's wavelengths of proton, neutron, electron and α particle respectively, then choose the correct relation from the following:$ (1) $λ_{p} = λ_{n} > λ_{e} > λ_{α}$ (2) $λ_{α} < λ_{n} < λ_{p} < λ_{e}$ (3) $λ_{e} < λ_{p} = λ_{n} > λ_{α}$ (4) $λ_{e} = λ_{p} = λ_{n} = λ_{α}$ 228. $If a source of electromagnetic radiation having power 15 kW produces 1 0^{16} photons per second, the radiation belongs to a part of spectrum is. (Take Planck constant h = 6 x 1 0^{- 34} Js)$ (1) $Microwaves$ (2) $Ultraviolet rays$ (3) $Gamma rays$ (4) $Radio waves$ 229. $A sub-atomic particle of mass 10^{- 30} kg is moving with a velocity 2.21 \times 10^{6} m / s . Under the matter wave consideration, the particle will behave closely like (h = 6.63 \times 10^{- 34} J . s)$ (1) $Visible radiation$ (2) $Gamma rays$ (3) $Infra-red radiation$ (4) $X-rays$ 230. $From a metallic surface photoelectric emission is observed for frequencies v_{1} and v_{2} (v_{1} > v_{2}) of the incident light. The maximum values of the kinetic energy of the photoelectrons emitted in the two cases are in the ratio 1 : x . Hence the threshold frequency of the metallic surface is$ (1) $\frac{v _{1} - v _{2}}{x}$ (2) $\frac{v _{1} - v _{2}}{x - 1}$ (3) $\frac{x v _{1} - v _{2}}{x - 1}$ (4) $\frac{x v _{2} - v _{1}}{x}$ 231. $The de Broglie wavelength of an electron accelerated to a potential of 400 V is approximately$ (1) $0.03 nm$ (2) $0.04 nm$ (3) $0.12 nm$ (4) $0.06 nm$ 232. $Light of wavelength λ_{A} and λ_{B} falls on two identical metal plates A and B respectively. The maximum kinctic energy of photoclectrons is K_{A} and K_{B} respectively; then which one of the following relations is true? (λ_{A} = 2 λ_{B})$ (1) $K_{A} < \frac{K _{B}}{2}$ (2) $2 K_{A} = K_{B}$ (3) $K_{A} = 2 K_{B}$ (4) $K_{A} > 2 K_{B}$ 233. $In photoelectric experiment the stopping potential was measured to be ' V_{1}' and ' V_{2}' volt with incident light of wavelength ' λ' and \frac{λ}{2} respectively. The value of V_{2} is (φ_{0} =) work function, e = electronic charge)$ (1) $2 V_{1} + \frac{φ _{0}}{e}$ (2) $V_{1} - \frac{2 φ _{0}}{e}$ (3) $V_{1} + \frac{2 φ _{0}}{e}$ (4) $2 V_{1} - \frac{φ _{0}}{e}$ 234. $Number of photons of equal energy emitted per second by a 6 mW laser source operating at 663 nm is____. (Given: h = 6.63 \times 10^{- 34} J . s and c = 3 \times 10^{8} m / s)$ (1) $2 \times 10^{16}$ (2) $10 \times 10^{15}$ (3) $5 \times 10^{15}$ (4) $5 \times 10^{16}$ 235. $The de Broglie wavelengths of a proton and an α particle are λ and 2 λ respectively. The ratio of the velocities of proton and α particle will be:$ (1) $1 : 8$ (2) $1 : 2$ (3) $4 : 1$ (4) $8 : 1$ 236. $The kinetic energy of an electron, which is accelerated in the potential difference of 100 volts, is$ (1) $416.6 cal$ (2) $6.636 cal$ (3) $1.602 \times 1 0^{- 17} J$ (4) $1.6 \times 1 0^{4} J$ 237. $G.P. Thomson experimentally confirmed the existence of matter waves by the phenomena$ (1) $diffraction$ (2) $refraction$ (3) $polarisation$ (4) $scattering.$ 238. $The momentum of a photon of energy 1 MeV in kg m / s will be$ (1) $5\times 1 0^{- 22}$ (2) $0.33 \times 1 0^{6}$ (3) $7 \times 1 0^{- 24}$ (4) $1 0^{- 22}$ 239. $In photoelectric emission process from a metal of work function 1.8 eV, the kinetic energy of most energetic electrons is 0.5 eV The corresponding stopping potential is$ (1) $1.8 V$ (2) $1.3 V$ (3) $0.5 V$ (4) $2.3 V$ 240. $If particles are moving with same velocity, then which has maximum de Broglie wavelength?$ (1) $proton$ (2) $α ‐particle$ (3) $neutron$ (4) $β ‐particle.$