Dual Nature of Matter & Radiation PYQs Set 5 (PDF)

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Mere Teacher · Previous Year Questions NEET Physics · Dual Nature of Matter & Radiation · Set 5 (Q121-150)
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121. $An electron accelerated through a potential difference V_{1} has a de-Broglie wavelength of λ . When the potential is changed to V_{2}, its de-Broglie wavelength increases by 50%. The value of (\frac{V _{1}}{V _{2}}) is equal to:$ (1) $3$ (2) $\frac{9}{4}$ (3) $\frac{3}{2}$ (4) $4$ 122. $The de Broglie wavelength of an oxygen molecule at 27^{\circ} C is x \times 10^{- 12} m . The value of x is (take Planck's constant = 6.63 \times 10^{- 34} J . s, Boltzmann constant = 1.38 \times 10^{- 23} J / K, mass of oxygen molecule = 5.31 \times 10^{- 26} kg)$ (1) $24$ (2) $26$ (3) $30$ (4) $20$ 123. $If c is the velocity of light in free space, the correct statements about photon among the following are(A) The energy of a photon is E = hv .(B) The velocity of a photon is c.(C) The momentum of a photon, p = \frac{hv}{c} (D) In a photon-electron collision, both total energy and total momentum are conserved.(E) Photon possesses positive charge. Choose the correct answer from the options given below. [NEET 2024]$ (1) $(A) and (B) only$ (2) $(A), (B), (C) and (D) only$ (3) $(A), (C) and (D) only$ (4) $(A), (B), (D) and (E) only$ 124. $An α particle and a carbon 12 atom has same kinetic energy K. The ratio of their de-Broglie wavelength (λ_{α} : λ_{C 12}) is:$ (1) $1 : 3$ (2) $3 : 1$ (3) $3 : 1$ (4) $2 : 3$ 125. $Two light waves of wavelengths 600 nm and 200 nm incident on a metal surface. The maximum velocity of photoelectrons produced due to one wavelength is \frac{1}{3} of the maximum velocity of the photoelectrons produced due to the other wavelength, then the work function of the metal is$ (1) $\frac{hc}{8} \times 10^{7} J$ (2) $\frac{8}{hc} \times 10^{7} J$ (3) $\frac{hc}{4} \times 10^{7} J$ (4) $\frac{hc}{9} \times 10^{7} J$ 126. $If the two metals A and B are exposed to radiation of wavelength 350 nm. The work functions of metals A and B are 4.8 eV and 2.2 eV. Then choose the correct option$ (1) $Metal B will not emit photo-electrons$ (2) $Both metals A and B will emit photo-electrons$ (3) $Both metals A and B will not emit photo- electrons$ (4) $Metal A will not emit photo-electrons$ 127. $The radiation pressure exerted by a 450 W light source on a perfectly reflecting surface placed at 2 m away from it, is$ (1) $3 \times 10^{- 8} Pascals$ (2) $0$ (3) $1.5 \times 10^{- 8} Pascals$ (4) $6 \times 10^{- 8} Pascals$ 128. $The work function of a photosensitive material is 4.0 eV. This longest wavelength of light that can cause photon emission from the substance is (approximately) [NEET 2019]$ (1) $3100 nm$ (2) $966 nm$ (3) $31 nm$ (4) $310 nm$ 129. $When monochromatic light falls on a photo-sensitive metal, an electron is emitted with maximum velocity 1.6 \times 10^{6} m / s . Find the stopping potential. [charge of electron = 1.6 \times 10^{- 19} C, mass of electron (= 9 \times 10^{- 31} kg)$ (1) $7.2 V$ (2) $14.4 V$ (3) $21.6 V$ (4) $28.8 V$ 130. $Monochromatic light of frequency 6 \times 10^{14} Hz is produced by a laser. The power emitted is 2 \times 10^{- 3} W . How many photons per second on an average, are emitted by the source? (Given (h = 6.63 \times 10^{- 34} Js)$ (1) $9 \times 10^{18}$ (2) $6 \times 10^{15}$ (3) $5 \times 10^{15}$ (4) $7 \times 10^{16}$ 131. $The momentum of a photon of an electromagnetic radiation is 3.3 \times 1 0^{- 29} kgm s^{- 1} . What is the frequency of the associated waves7. [h = 6.6 \times 1 0^{- 34} Js; c = 3 \times 1 0^{8} m s^{- 1}]$ (1) $1.5 \times 1 0^{13} Hz$ (2) $7.5 \times 1 0^{12} Hz$ (3) $6 \times 1 0^{3} Hz$ (4) $3 \times 1 0^{3} Hz$ 132. $Photons of energy 2.4 eV and wavelength λ fall on a metal plate and release photoelectrons with a maximum velocity v . By decreasing λ by 50 %, the maximum velocity of photoelectrons becomes 3 v . The work function of the material of the metal plate is$ (1) $2.1 eV$ (2) $1.7 eV$ (3) $2.8 eV$ (4) $2.0 eV$ 133. $When light of wavelength λ is incident on photosensitive surface, the stopping potential is V . When light of wavelength 3 λ is incident on same surface, the stopping potential is \frac{V}{6} . Threshold wavelength for the surface is$ (1) $2 λ$ (2) $3 λ$ (3) $4 λ$ (4) $5 λ$ 134. $A photo sensitive metallic surface emits electrons when X-rays of wavelength λ fall on it. The de-Broglie wavelength of the emitted electrons is (Neglect the work function of the surface, m is mass of the electron, h is Planck's constant, c is the velocity of light)$ (1) $\frac{2 mc}{hλ}$ (2) $\frac{hλ}{2 mc}$ (3) $\frac{mc}{hλ}$ (4) $\frac{hλ}{mc}$ 135. $A photosensitive metallic surface has work function, h ν_{0} . If photons of energy 2 h ν_{0} fall on this surface, the electrons come out with a maximum velocity of 4 \times 1 0^{6} m / s . When the photon energy is increased to 5 h ν_{0}, then maximum velocity of photoelectrons will be$ (1) $2 \times 1 0^{7} m / s$ (2) $2 \times 1 0^{6} m / s$ (3) $8 \times 1 0^{6} m / s$ (4) $8 \times 1 0^{5} m / s$ 136. $A particle of mass 1 \times 10^{- 30} kg and electric change 1.6 \times 10^{- 19} C has de-Broglie wavelength 660 nm . Then kinetic energy of this particle is (Plank's constant, h = 6.6 \times 10^{- 34} J - s)$ (1) $4.2 \times 10^{- 6} eV$ (2) $2.5 \times 10^{- 6} eV$ (3) $1.3 \times 10^{- 6} eV$ (4) $3.1 \times 10^{- 6} eV$ 137. $In photoelectric experiment energy of 2.48 eV irradiates a photo sensitive material. The stopping potential was measured to be 0.5 V . Work function of the photo sensitive material is:$ (1) $1.68 eV$ (2) $2.48 eV$ (3) $1.98 eV$ (4) $0.5 eV$ 138. $Which figure shows the correct variation of applied potential difference (V) with photoelectric current (I) at two different intensities of light (I_{1} < I_{2}) of same wavelengths:$ (1) (2) (3) (4) 139. $The de Broglie wavelength of a particle moving with a speed of 0.8 c is equal to the wavelength of a photon. If c is speed of the photon in vacuum, the ratio of the energy of the photon and the kinetic energy of the particle is$ (1) $2 : 3$ (2) $5 : 2$ (3) $4 : 5$ (4) $3 : 5$ 140. $An electron with mass ' m' with an initial velocity (t = 0) v = v_{0} i (v_{0} > 0) enters a magnetic field B = B_{0} j . If the initial deBroglie wavelength at t = 0 is λ_{0} then its value after time ' t ' would be:$ (1) $\frac{λ _{0}}{1 - \frac{e ^{2} B _{0}^{2} t ^{2}}{m ^{2}}}$ (2) $λ_{0}$ (3) $λ_{0} 1 + \frac{e ^{2} B _{0}^{2} t ^{2}}{m ^{2}}$ (4) $\frac{λ _{0}}{1 + \frac{e ^{2} B _{0}^{2} t ^{2}}{m ^{2}}}$ 141. $A parallel beam of light of wavelength 900 nm and intensity 100 W m^{- 2} is incident on a surface perpendicular to the beam. Tire number of photons crossing 1 c m^{2} area perpendicular to the beam in one second is:$ (1) $3 x 1 0^{16}$ (2) $4.5 x 1 0^{16}$ (3) $4.5 x 1 0^{17}$ (4) $4.5 x 1 0^{20}$ 142. $When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V . If the same surface is illuminated with radiation of wavelength 2 λ, the stopping potential is \frac{V}{4} . The threshold wavelength for the metallic surface is$ (1) $\frac{5}{2} λ$ (2) $3 λ$ (3) $4 λ$ (4) $5 λ$ 143. $A proton and an electron have the same de Broglie wavelength. If K_{p} and K_{e} be the kinetic energies of proton and electron respectively, then choose the correct relation:$ (1) $K_{p} > K_{e}$ (2) $K_{p} < K_{e}$ (3) $K_{p} = K_{e}$ (4) $K_{p} = K_{e}^{2}$ 144. $The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (kelvin) and mass m, is [NEET 2017]$ (1) $\frac{h}{mkT}$ (2) $\frac{h}{3 mkT}$ (3) $\frac{2 h}{3 mkT}$ (4) $\frac{2 h}{mkT}$ 145. $An electron is accelerated through a potential difference of 10,000 V Its de Broglie wavelength is, (nearly) (m_{e} = 9 \times 1 0^{- 31} kg)$ (1) $12.2 nm$ (2) $12.2 \times 1 0^{- 13} m$ (3) $12.2 \times 1 0^{- 12} m$ (4) $12.2 \times 1 0^{- 14} m$ 146. $When ultraviolet rays incident on metal plate then photoelectric effect does not occur, it occurs by incidence of$ (1) $infrared rays$ (2) $X ‐rays$ (3) $radio wave$ (4) $microwave.$ 147. $Light strikes a metal surface causing photoelectric emission. The wavelength of incident light is 248 nm . If the stopping potential for the ejected electrons is 2.8 eV, then the work function of the metal is (Take hc = 1240 eV . nm)$ (1) $5.2 eV$ (2) $4.4 eV$ (3) $3.8 eV$ (4) $2.2 eV$ 148. $A radiation of 3.8 eV falls on a metal surface to produce photo electrons. These electrons are made to enter a magnetic field of 2 \times 10^{- 4} T . If the radius of the largest circular path followed by these electrons is 30 mm, then work function of the metal is (Mass of electron m_{e} = 9 \times 10^{- 31} kg)$ (1) $0.9 eV$ (2) $1.0 eV$ (3) $0.6 eV$ (4) $1.2 eV$ 149. $An electron of mass m, when accelerated through a potential difference V, has de Broglie wavelength λ . The de Broglie wavelength associated with a proton of mass M accelerated through the same potential difference, will be$ (1) $λ \frac{M}{m}$ (2) $λ \frac{m}{M}$ (3) $λ \frac{M}{m}$ (4) $λ \frac{m}{M}$ 150. $If we consider electrons and photons of same wavelength, then they will have same$ (1) $momentum$ (2) $angular momentum$ (3) $energy$ (4) $velocity.$