Title 11.DUAL NATURE OF RADIATION AND MATTER - Questions.pdf ✅

11.DUAL NATURE OF RADIATION AND MATTER (1.)If light of wavelength λ1 is allowed to fall on a metal, then kinetic energy of photoelectrons emitted is E1. If wavelength of light changes to λ2 then kinetic energy of electrons changes to E2. Then work function of the metal is (a.) E1E2(λ1−λ2) λ1λ2 (b.) E1λ1−E2λ2 (λ1−λ2) (c.) E1λ1−E2λ2 (λ2−λ1) (d.) λ1λ2E1E2 (λ2−λ1) (2.)Vidicon works on the principle of (a.) Electrical conductivity (b.) Photoconductivity (c.) Thermal conductivity (d.) SONAR (3.)If the kinetic energy of the particle is increased by 16 times, the percentage change in the de Broglie wavelength of the particle is (a.) 25% (b.) 75% (c.) 60% (d.) 50% (4.)The X-ray wavelength of Lα line of platinum (Z = 78) is 1.30Å. The X-ray wavelength of Lα line of Molybdenum (Z = 42) is (a.) 5.41 Å (b.) 4.20 Å (c.) 2.70 Å (d.) 1.35 Å (5.)There are n1 photons of frequency v1 in a beam of light. In an equally energetic beam there are n2 photons of frequency v2. Then the correct relation (a.) n1 n2 = v1 v2 (b.) n1 n2 = 1 (c.) n1 n2 = v2 v1 (d.) n1 n2 = v2 2 v1 2 (6.)Photons of energy of 6 eV are incident on a metal surface whose work function is 4 eV. The minimum kinetic energy of the emitted photoelectrons will be (a.) Zero (b.) 1 eV (c.) 2 eV (d.) 10 eV (7.)For the production of X-rays, the target should be made of (a.) Steel (b.) Copper (c.) Aluminimum (d.) Tungsten (8.)Irreducible area a b c d, in figure is (a.) Work (b.) Plank’s constant (c.) Joule (d.) Charge (9.)Bragg’s law for X-rays is (a.) d sin θ = 2nλ (b.) 2d sinθ = nλ (c.) n sin θ = 2λd (d.) None of these (10.)A tiny spherical oil drop carrying a net charge q is balanced in still air with vertical uniform electric field of strength 81π 7 × 105Vm−1 .When the field is switched off, the drop is observed to fall with terminal velocity 2 × 10−3ms−1 . Given g = 9.8 ms−2 , viscosity of the air =1.8 × 10−5Ns m−2 and the density of oil = 900 kg m−3 , the magnitude of q is (a.) 1.6 × 10−19 C (b.) 3.2 × 10−19 C (c.) 4.8 × 10−19 C (d.) 8.0× 10−19 C (11.)A parallel beam of light is incident normally on a plane surface absorbing 40% of the light and reflecting the rest. If the incident beam carries 60 W of power, the force exerted by it on the surface is (a.) 3.2 × 10−8N (b.) 3.2 × 10−7N (c.) 5.12 × 10−7N (d.) 5.12 × 10−8N (12.)From the figure describing photoelectric effect we may infer correctly that
(a.) Na and Al both have the same threshold frequency (b.) Maximum kinetic energy for both the metals depend linearly on the frequency (c.) The stopping potentials are different for Na and Al for the same change in frequency (d.) Al is a better photo sensitive material than Na (13.)The characteristic X-rays radiation is emitted, when (a.) The electrons are accelerated to a fixed energy (b.) The source of electrons emits a monoenergetic beam (c.) The bombarding electrons knock out electrons from the inner shell of the target atoms and one of the outer electrons falls into this vacancy (d.) The valence electrons in the target atoms are removed as a result of the collision (14.)In X-ray experiment Kα,Kβ denotes (a.) Characteristic (b.) Continuous wavelength (c.) α, β-emissions respectively (d.) None of these (15.)The electrons are emitted in the photoelectric effect from a metal surface (a.) Only if the frequency of the incident radiation is above a certain threshold value (b.) Only if the temperature of the surface is high (c.) At a rate that is independent of the nature of the metal (d.) With a maximum velocity proportional to the frequency of the incident radiation (16.)The ratio of the energy of an X-ray photon of wavelength 1 Å to that of visible light of wavelength 5000 Å is (a.) 1 :5000 (b.) 5000 :1 (c.) 1: 25 × 106 (d.) 25 × 106 (17.)What is the de-Broglie wavelength (in Å) of the α-particle accelerated through a potential difference V? (a.) 0.287 √V (b.) 12.27 √V (c.) 0.101 √V (d.) 0.22 √V (18.)The ratio of the energy of a photon with λ = 150 nm to that with λ = 300 nm is (a.) 2 (b.) 1 4 (c.) 4 (d.) 1 2 (19.)Who discovered the charge on an electron for the first time? (a.) Millikan (b.) Thomson (c.) Kelvin (d.) Coulomb (20.)The potential difference applied to an X-ray tube is 5 kV and the current through it is 3.2 mA. The number of electrons striking the target per second is (Take e =1.6 × 10−19 C) (a.) 1.6 × 106 (b.) 2 × 10 −6 (c.) 4 × 1016 (d.) 2 × 1016 (21.)An important spectral emission line has a wavelength of 21cm. The corresponding photon energy is (h = 6.62 × 10−34 Js and c = 3 × 108 ms −1 ) (a.) 5.9 × 10−8 eV (b.) 5.9 × 10−4 eV (c.) 5.9 × 10−6 eV (d.) 11.8 × 10−6 eV (22.)Cathode rays are similar to visible light rays as (a.) They both can be deflected by electric and magnetic fields (b.) They both have a definite magnitude of wavelength (c.) They both can ionize a gas through which they pass (d.) They both can expose a photographic plate (23.)Photoelectric effect is an example of (a.) Elastic collision (b.) Inelastic collision (c.) Two dimensional collision (d.) Oblique collision (24.)Which of the following supports the wave nature of X-rays? (a.) Photoelectric effect
(b.) Photosynthesis (c.) Compton scattering (d.) Diffraction (25.)When a cathode ray tube is operated at 2912 V, the velocity of electrons is 3.2 × 107m/s. Find the velocity of cathode ray if the tube is operated at 5824 V (a.) 2.4 × 107 m/s (b.) 5.2 × 107 m/s (c.) 4.525 × 107 m/s (d.) 2.4 × 106 m/s (26.)Momentum of a photon of wavelength λ is (a.) h/λ (b.) hλ/c 2 (c.) h λ/c (d.) Zero (27.)The frequency of a photon, having energy 100 eV is (h = 6.6 × 10−34J-s) (a.) 2.42 × 1026Hz (b.) 2.42 × 1016Hz (c.) 2.42 × 1012Hz (d.) 2.42 × 109Hz (28.)The wavelength λ of the Kα line of characteristic X-rays spectra varies with atomic number approximately (a.) λ ∝ Z (b.) λ ∝ √Z (c.) λ ∝ 1 Z2 (d.) λ ∝ 1 √Z (29.)The stopping potential (V0) (a.) Depends upon the angle of incident light (b.) Depends upon the intensity of incident light (c.) Depends upon the surface nature of the substances (d.) Is independent of the intensity of the incident light (30.)Energy required to remove an electron from an aluminium surface is 4.2 eV. If light of wavelength 2000 Å falls on the surface, the velocity of fastest electrons ejected from the surface is (a.) 2.5 × 1018ms −1 (b.) 2.5 × 1013ms −1 (c.) 6.7 × 1018ms −1 (d.) None of these (31.)The photoelectric threshold wavelength for potassium (work function being 2 eV) is (a.) 310 nm (b.) 620 nm (c.) 1200 nm (d.) 2100 nm (32.)The photo-electrons emitted from a surface of sodium metal are such that (a.) They all are of the same frequency (b.) They have the same kinetic energy (c.) They have the same de Broglie wavelength (d.) They have their speeds varying from zero to a certain maximum (33.)X-rays of wavelength 0.140 nm are scattered from a block of carbon. What will be the wavelenghts of X-rays scattered at 900 ? (a.) 0.140 nm (b.) 0.142 nm (c.) 0.144 nm (d.) 0.146 nm (34.)The minimum wavelength of X-ray emitted by X-rays tube is 0.4125 Å. The accelerating voltage is (a.) 30 kV (b.) 50 kV (c.) 80 kV (d.) 60 kV (35.)Light of wavelength 5000 Å falls on a sensitive plate with photoelectric work functional of 1.9 eV. The kinetic energy of the photoelectron emitted will be (a.) 0.58 eV (b.) 2.48 eV (c.) 1.24 eV (d.) 1.16 eV (36.)Electron with energy 80 keV are incident on the tungsten target of a X-rays tube. K shell electrons of tungsten have −72.5 keV energy. X- rays emitted by the tube contain only (a.) A continuous X-rays spectrum (Bremsstrahlung) with a minimum wavelength of ~0.155Å (b.) A continuous X-ray spectrum (Bremsstrahlung) with all wavelengths (c.) The characteristic X-rays spectrum of tungsten (d.) A continuous X-rays spectrum (Bremsstrahlung) with a minimum wavelength of ~0.155 Å and the characteristic X-rays spectrum of tungsten (37.)For harder X-rays (a.) The wavelength is higher (b.) The intensity is higher (c.) The frequency is higher (d.) The frequency is higher (38.)In an ionisation experiment it is found that a doubly ionised particle enters a magnetic field of 1 T and moves in a circular path of radius 1 m with a speed of 1.6 × 107 ms −1 . The particle must be (a.) C ++ (b.) Be ++ (c.) Li ++ (d.) He ++ (39.)A proton of mass 1.67 × 10−27 kg enters a uniform magnetic field of 1 T at point A as shown in
figure, with a speed of 107 ms −1 . The magnetic field is directed normal to the plane of paper downwards. The proton emerges out of the magnetic field at point C, then the distance AC and the value of angle θ will respectively be (a.) 0.7 m, 45° (b.) 0.7 m, 90° (c.) 0.14 m, 90° (d.) 0.14 m, 45° (40.)The value of Plank energy is (a.) nhc λ (b.) nhλ (c.) nhcλ (d.) nhλ c (41.)A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity, then (a.) Its velocity will decrease (b.) Its velocity will increase (c.) It will turn towards right of direction of motion (d.) It will turns towards left of direction of motion (42.)Among the following four spectral regions, the photons has the highest energy in (a.) Infrared (b.) Violet (c.) Red (d.) Blue (43.)A caesium photocell, with a steady potential difference of 60V across, is illuminated by a bright point source of light 50 cm away. When the same light is placed 1m away the photoelectrons emitted from the cell (a.) Are one quarter as numerous (b.) Are half as numerous (c.) Each carry one quarter of their previous momentum (d.) Each carry one quarter of their previous energy (44.)Hard X-ray for the study of fractures in bones should have a minimum wavelength of 10−11 m. The accelerating voltage for electrons in X-ray machine should be (a.) <124 kV (b.) >124 kV (c.) Between 60 kV and 70 kV (d.) =100 kV (45.)Which one of the following is true in photoelectric emission (a.) Photoelectric current is directly proportional to the amplitude of light of a given frequency (b.) Phototelectric current is directly proportional to the intensity of light of a given frequency at moderate intensities (c.) Above the threshold frequency, the maximum K.E. of photoelectrons is inversely proportional to the frequency of incident light (d.) The threshold frequency depends upon the wavelength of incident light (46.)Which of the following is dependent on the intensity of incident radiation in a photoelectric experiment (a.) Work function of the surface (b.) Amount of photoelectric current (c.) Stopping potential will be reduced (d.) Maximum kinetic energy of photoelectrons (47.)X-rays are (a.) Stream of electrons (b.) Stream of positively charged particles (c.) Electromagnetic radiantions of high frequency (d.) Stream of uncharged particles (48.)An α-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m2 . The de Broglie wavelength associated with the particle will be (a.) 1 Å (b.) 0.1 Å (c.) 10 Å (d.) 0.01 Å (49.)de-Broglie hypothesis treated electrons as (a.) Particles (b.) Waves (c.) Both ′a′ and ′b′ (d.) None of these (50.)A particle of charge −16 × 10−18 C moving with velocity 10 ms−1 along the x-axis enters a region where a magnetic field of induction B is along the y-axis and an electric field of magnitude 104 Vm−1 is along the negative z-axis. If the charged particle continues moving along the x-axis, the magnitude of B is (a.) 103Wbm−2 (b.) 105Wbm−2 (c.) 1016Wbm−2 (d.) 10−3Wbm−2 (51.)Choose the correct answer (a.) Photoelectric effect can take place from bound electron (b.) Photoelectric effect can take place from free electron