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12th Standard English Medium Physics Subject Dual Nature of Radiation and Matter Book Back 1 Mark Questions with Solution Part - I

12th Standard

    Reg.No. :
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Physics

Time : 00:30:00 Hrs
Total Marks : 5

    Part I

    5 x 1 = 5
  1. In an electron microscope, the electrons are accelerated by a voltage of 14 kV. If the voltage is changed to 224 kV, then the de Broglie wavelength associated with the electrons would _____.

    (a)

    increase by 2 times

    (b)

    decrease by 2 times

    (c)

    decrease by 4 times

    (d)

    increase by 4 times

  2. 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 2λ, the stopping potential is \(\frac{V}{4}\). The threshold wavelength for the metallic surface is _____.

    (a)

    (b)

    (c)

    \(\frac{5}{2}λ\)

    (d)

  3. A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and λ /2. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the material is _____.

    (a)

    \(\frac{hc}{\lambda}\)

    (b)

    \(\frac{2hc}{\lambda}\)

    (c)

    \(\frac{hc}{3\lambda}\)

    (d)

    \(\frac{hc}{2\lambda}\)

  4. Two radiations with photon energies 0.9 eV and 3.3 eV respectively are falling on a metallic surface successively. If the work function of the metal is 0.6 eV, then the ratio of maximum speeds of emitted electrons in the two cases will be _____.

    (a)

    1:4

    (b)

    1:3

    (c)

    1:1

    (d)

    1:9

  5. If the mean wavelength of light from sun is taken as 550 nm and its mean power as 3.8 x 1026 W, then the number of photons emitted per second from the sun is of the order of _____.

    (a)

    1045

    (b)

    1042

    (c)

    1054

    (d)

    1051

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