Dual Nature of Matter & Radiation PYQs Set 10 (PDF)

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Mere Teacher · Previous Year Questions NEET Physics · Dual Nature of Matter & Radiation · Set 10 (Q271-300)
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271. $In a photoelectric experiment three different lights are incident on a metal of work function 1.5 eV . Light A is 200 nm wavelength with intensity 1.8 W / m^{2}, light B is 400 nm with 1 W / m^{2} and light C is 600 nm with 0.5 W / m^{2} . The current versus voltage is measured. Which graphs correspond to which light? Light A Light B Light C$ (1) $I III II$ (2) $I II IV$ (3) $I III IV$ (4) $III II IV$ 272. $According to Einstein’s photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is$ (1) (2) (3) (4) 273. $The graph which shows the variation of the de-Broglie wavelength (λ) of a particle and its associated momentum (p) is [NEET 2022]$ (1) (2) (3) (4) 274. $In an experiment to study photo-electric effect the observed variation of stopping potential with frequency of incident radiation is as shown in the figure. The slope and y -intercept are respectively$ (1) $\frac{h}{e}, - \frac{h v _{0}}{e}$ (2) $\frac{hv}{e}, v_{0}$ (3) $\frac{hv}{e}, - \frac{h}{e}$ (4) $hv, - h v_{0}$ 275. $The following graph represents the variation of photo current with anode potential for a metal surface. Here I_{1}, I_{2} and I_{3} represents intensities and γ_{1}, γ_{2}, γ_{3} represent frequency$ (1) $γ_{1} = γ_{2} and I_{1} \neq = I_{2}$ (2) $γ_{1} = γ_{3} and I_{1} \neq = I_{3}$ (3) $γ_{1} = γ_{2} and I_{1} = I_{2}$ (4) $γ_{2} = γ_{3} and I_{1} = I_{3}$ 276. $The graph which shows the variation of \frac{1}{λ ^{2}} and its kinetic energy, E is (where, λ is de-Broglie wavelength of a free particle) [NEET 2024]$ (1) (2) (3) (4) 277. $The variation of photo-current with collector potential for different frequencies of incident radiation v_{1}, v_{2} and v_{3} is as shown in the graph, then$ (1) $v_{1} = v_{2} = v_{3}$ (2) $v_{1} > v_{2} > v_{3}$ (3) $v_{1} < v_{2} < v_{3}$ (4) $v_{3} = \frac{v _{1} + v _{2}}{2}$ 278. $The graph given in the figure shows the variation of photo current (I) and the applied voltage (V) for two different materials and for two different intensities of the incident radiations. Then the curves which represent the same material are$ (1) $1 and 3$ (2) $1 and 4$ (3) $2 and 3$ (4) $3 and 4$ 279. $For photoelectric emission from certain metal the cutoff frequency is ν . If radiation of frequency 2 ν impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass)$ (1) $\frac{2 h ν}{m}$ (2) $2 \frac{h ν}{m}$ (3) $\frac{h ν}{( 2 m )}$ (4) $\frac{h ν}{m}$ 280. $If a photon has velocity c and frequency, v then which of the following represents its wavelength?$ (1) $\frac{h ν}{c ^{2}}$ (2) $h ν$ (3) $\frac{h c}{E}$ (4) $\frac{h ν}{c}$ 281. $In a photoelectric experiment, a graph is drawn with stopping potential along Y-axis and the frequency of the incident light along X -axis. If the graph is a straight line which makes an angle θ with Y-axis, then tan θ = (h-planck's constant, e-charge of electron)$ (1) $\frac{h}{e}$ (2) $\frac{e}{h}$ (3) $\frac{h}{e}$ (4) $\frac{e}{h}$ 282. $Light of energy 4.13 e V is incident on a surface having work function 3.13 e V . The maximum kinetic energy of ejected photoelectrons will be:$ (1) $4.13 eV$ (2) $3.13 eV$ (3) $1 eV$ (4) $7.26eV$ 283. $Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: In photoelectric effect, on increasing the intensity of incident light the stopping potential increases. Reason R: Increase in intensity of light increases the rate of photoelectrons emitted, provided the frequency of incident light is greater than threshold frequency. In the light of the above statements, choose the correct answer from the options given below$ (1) $Both A and R are true and R is the correct explanation of A$ (2) $A is false but R is true$ (3) $Both A and R are true but R is NOT the correct explanation of A$ (4) $A is true but R is false$ 284. $The maximum kinetic energy of a photoelectron liberation from the surface of lithium with work function 2.35 eV by electromagnetic radiation whose electric component varies with time as : E = a (1 + cos (2 π f_{1} t)) cos 2 π f_{2} t (where a is a constant) is (f_{1} = 3.6 \times 10^{15} Hz), and f_{2} = 1.2 \times 10^{15} Hz and Planck's constant h = 6.6 \times 10^{- 34} Js)$ (1) $2.64 eV$ (2) $7.55 eV$ (3) $12.52 eV$ (4) $17.45 eV$ 285. $A monochromatic light is incident on a metallic plate having work function φ . An electron, emitted normally to the plate from a point A with maximum kinetic energy, enters a constant magnetic field, perpendicular to the initial velocity of electron. The electron passes through a curve and hits back the plate at a point B . The distance between A and B is: (Given: The magnitude of charge of an electron is e and mass is m, h is Planck's constant and c is velocity of light. Take the magnetic field exists throughout the path of electron)$ (1) $2 m (\frac{hc}{λ} - φ) / eB$ (2) $8 m (\frac{hc}{λ} - φ) / eB$ (3) $m (hc / λ - φ) / eB$ (4) $2 m (hc / λ - φ) / eB$ 286. $Thermions are$ (1) $protons$ (2) $electrons$ (3) $photons$ (4) $positrons$ 287. $Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: The photoelectric effect does not take place, if the energy of the incident radiation is less than the work function of a metal. Reason R: Kinetic energy of the photoelectrons is zero, if the energy of the incident radiation is equal to the work function of a metal. In the light of the above statements, choose the most appropriate answer from the options given below.$ (1) $Both A and R are correct and R is the correct explanation of A$ (2) $Both A and R are correct but R is not the correct explanation of A$ (3) $A is correct but R is not correct$ (4) $A is not correct but R is correct$ 288. $The value of Planck’s constant is$ (1) $6.63 \times 1 0^{- 34} J / sec$ (2) $6.63\times 1 0^{- 34} kg-m2/ sec$ (3) $6.63 \times 1 0^{- 34} kg - m^{2}$ (4) $6.63 \times 1 0^{- 34} J - sec .$ 289. $With reference to the observations in photo-electric effect, identify the correct statements from below: (A) The square of maximum velocity of photoelectrons varies linearly with frequency of incident light. (B) The value of saturation current increases on moving the source of light away from the metal surface, (C) The maximum kinetic energy of photo-electrons decreases on decreasing the power of LED (light emitting diode) source of light. (D) The immediate emission of photo-electrons out of metal surface cannot be explained by particle nature of light/electromagnetic waves. (E) Existence of threshold wavelength cannot be explained by wave nature of light/electromagnetic waves. Choose the correct answer from the options given below:$ (1) $A and B only$ (2) $A and E only$ (3) $C and E only$ (4) $D and E only$ 290. $From the photoelectric effect experiment, following observations are made. Identify which of these are correct (A) The stopping potential depends only on the work function of the metal (B) The saturation current increases as the intensity of incident light increases. (C) The maximum kinetic energy of a photo electron depends on the intensity of the incident light. (D) Photoelectric effect can be explained using wave theory of light. Choose the correct answer from the options given below:$ (1) $B, C only$ (2) $A, C, D only$ (3) $B only$ (4) $A, B, D only$ 291. $In photoelectric effect, the stopping potential V0v/s frequency (ν) curve is plotted. (h is the Planck's constant and φ_{0} is work function of metal) (A) V0v/sv is linear. (B) The slope of V0v/sv curve = \frac{φ _{0}}{h} (C) h constant is related to the slope of V0v/sv line. (D) The value of electric charge of electron is not required to determine h using the V0v/sv curve. (E) The work function can be estimated without knowing the value of h. Choose the correct answer from the options given below:$ (1) $(C) and (D) only$ (2) $(A), (C) and (E) only$ (3) $(A), (B) and (C) only$ (4) $(D) and (E) only$ 292. $In photoelectric effect (A) The photocurrent is proportional to the intensity of the incident radiation. (B) Maximum kinetic energy with which photoelectrons are emitted depends on the intensity of incident light. (C) Max K.E. with which photoelectrons are emitted depends on the frequency of incident light. (D) The emission of photoelectrons require a minimum threshold intensity of incident radiation. Choose the correct answer from the options given below: ($ (1) $A and B only$ (2) $A and E only$ (3) $A and C only$ (4) $B and C only$ 293. $Statement (I): By increasing the potential difference between cathode and anode continuously in a photoelectric experiment, the photo current always increases continuously. Statement (II): If two photons A and B of energies 2.5 eV and 3.5 eV respectively fall on a metal surface of work function 2.0 eV, then the ratio of maximum kinetic energies emitted between A and B is 3 . Statement (III): The maximum energy needed by an electron to come out from metal surface is called the work function of the metal. Which of the following is correct?$ (1) $Statements I, II and III are true$ (2) $Statements I, II are true, but statement III is false$ (3) $Statements II, III are true, but statement I is false$ (4) $Statements I, II and III are false$ 294. $Given below are two statements: Statement-I: In hydrogen atom, the frequency of radiation emitted when an electron jumps from lower energy orbit (E1) to higher energy orbit (E2), is given as hf = E1 - E2. Statement-II: The jumping of electron from higher energy orbit (E2) to lower energy orbit (E1) is associated with frequency of radiation given as f = \frac{E _{2} - E _{1}}{h} This condition is Bohr's frequency condition. In the light of the above statements, choose the correct answer from the options given below:$ (1) $Both statement I and statement II are true.$ (2) $Both statement I and statement II are false$ (3) $Statement I is correct but statement II is false$ (4) $Statement I is incorrect but statement II is true.$ 295. $An electron of mass m with a velocity v = v_{0} (v_{0} > 0) enters an electric field E = - E_{0} (E_{0} = constant > 0) at t = 0 . If λ_{0} is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is [NEET 2018]$ (1) $λ_{0} t$ (2) $λ_{0} (1 + \frac{e E _{0}}{m v _{0}} t)$ (3) $\frac{λ _{0}}{( 1 + \frac{c E _{0}}{m v _{0}} t )}$ (4) $λ_{0}$ 296. $The light of two different frequencies whose photons have energies 3.8 eV and 1.4 eV respectively, illuminate a metallic surface whose work function is 0.6 eV successively. The ratio of maximum speeds of emitted electrons for the two frequencies respectively will be:$ (1) $1 : 1$ (2) $2 : 1$ (3) $4 : 1$ (4) $1 : 4$ 297. $The electromagnetic theory of light failed to explain$ (1) $photoelectric effect$ (2) $polarization$ (3) $diffraction$ (4) $interference.$ 298. $A photo‐cell is illuminated by a source of light, which is placed at a distance d from the cell. If the distance become d /2, then number of electrons emitted per second will be$ (1) $remain same$ (2) $four times$ (3) $two times$ (4) $one‐fourth$ 299. $By photoelectric effect, Einstein proved$ (1) $E = h ν$ (2) $K . E . = \frac{1}{2} m v^{2}$ (3) $E = m c^{2}$ (4) $E = \frac{- Rh c ^{2}}{n ^{2}}$ 300. $In a discharge tube at 0.02 mm, there is formation of$ (1) $Crooke’s dark space$ (2) $Faraday’s dark space$ (3) $both space partly$ (4) $none of these$