Dual Nature of Radiation and Matter

Dual Nature of Radiation and Matter

Easy Questions

Modern Physics

Dual Nature of Radiation and Matter
Atoms
Nuclei
Semiconductor Electronics : Materials, Devices and Simple Circuits
  1. An electron of mass m and charge e is accelerated from rest through a potential difference of V volt in vacuum. Its final speed will be








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    Kinetic energy of electron accelerated through a potential V= eV

    ⇒
    1
    		mv2 = eV
    2

    ⇒ v2 =
    2eV
    m

    ⇒ v =
    2eV
    m

    Correct Option: C

    Kinetic energy of electron accelerated through a potential V= eV

    ⇒
    1
    		mv2 = eV
    2

    ⇒ v2 =
    2eV
    m

    ⇒ v =
    2eV
    m

  1. The nature of ions knocked out from hot surfaces is








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    NA

    Correct Option: C

    NA

  1. If the threshold wavelength for a certain metal is 2000 Å, then the work-function of the metal is








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    Threshold wavelength (λ) = 2000 Å ​= 2000 × 10–10 m. Work function

    (W) =
    hc
    		=
    (6.6 × 1034) × (3 × 108)
    λ2000 × 10-10

    = 9.9× 10-19 J
    =
    9.9 × 10-19
    		= 6.2 eV
    1.6 × 10-19

    Correct Option: B

    Threshold wavelength (λ) = 2000 Å ​= 2000 × 10–10 m. Work function

    (W) =
    hc
    		=
    (6.6 × 1034) × (3 × 108)
    λ2000 × 10-10

    = 9.9× 10-19 J
    =
    9.9 × 10-19
    		= 6.2 eV
    1.6 × 10-19

  1. Kinetic energy of an electron, which is accelerated in a potential difference of 100 V is








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    Potential difference (V) = 100 V. The kinetic energy of an electron = 1 eV = 1 × (1.6 × 10–19)
    = 1.6 × 10–19 J. Therefore kinetic energy in
    100 volts = (1.6 × 10–19) × 100 = 1.6 × 10–17J.
    [Alt : K.E. = qV
    = 1.6 × 10–19 × 100 J = 1.6 × 10–17]

    Correct Option: A

    Potential difference (V) = 100 V. The kinetic energy of an electron = 1 eV = 1 × (1.6 × 10–19)
    = 1.6 × 10–19 J. Therefore kinetic energy in
    100 volts = (1.6 × 10–19) × 100 = 1.6 × 10–17J.
    [Alt : K.E. = qV
    = 1.6 × 10–19 × 100 J = 1.6 × 10–17]

  1. In photoelectric effect the work function of a metal is 3.5 eV. The emitted electrons can be stopped by applying a potential of ––1.2 V. Then








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    hν = W0 + Ek = 3.5 + 1.2 = 4.7 eV

    Correct Option: A

    hν = W0 + Ek = 3.5 + 1.2 = 4.7 eV