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. Doubly ionised helium atoms and hydrogen ions are accelerated from rest through the same potential drop. The ratio of the final velocities of the helium and the hydrogen ion is








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    =
    1
    		mv2 = eV
    2

    or , v = (2eV/m)1/2
    the mass of helium ion is four times that of hydrogen ion. Further, the charge on helium ion is twice that of hydrogen ion
    ∴
    vHe
    		= √2
    vH

    Correct Option: D

    =
    1
    		mv2 = eV
    2

    or , v = (2eV/m)1/2
    the mass of helium ion is four times that of hydrogen ion. Further, the charge on helium ion is twice that of hydrogen ion
    ∴
    vHe
    		= √2
    vH

  1. When light of wavelength 300 nm (nano meter) falls on a photoelectric emitter, photo electrons are liberated. For another emitter, however, light of 600 nm wavelength is sufficient for creating photo emission. What is the ratio of the work functions of the two emitters?








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    W0 =
    hc
    		or W0 ∝
    1
    		;
    λ0λ0

    ⇒
    W1
    		=
    λ2
    		=
    600
    		= 2
    W2λ1300

    Correct Option: B

    W0 =
    hc
    		or W0 ∝
    1
    		;
    λ0λ0

    ⇒
    W1
    		=
    λ2
    		=
    600
    		= 2
    W2λ1300

  1. Number of ejected photo electron increases with increase








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    Photoelectric current is directly proportional to the intensity of incident light.

    Correct Option: A

    Photoelectric current is directly proportional to the intensity of incident light.

  1. Which of the following statement is correct?








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    According to photoelectric effect, speed of electron (kinetic energy) emitted depends upon frequency of incident light while number of photo electrons emitted depends upon intensity of incident light. Hence, as the intensity of light increases, the photo current increases. In a photo-cell, the photo current has no relation with the applied voltage.
    ​Stopping potential is the (negative) potential at which the current is just reduced to zero. It is independent of intensity of light but depends on the frequency of light similar to K.E.

    Correct Option: A

    According to photoelectric effect, speed of electron (kinetic energy) emitted depends upon frequency of incident light while number of photo electrons emitted depends upon intensity of incident light. Hence, as the intensity of light increases, the photo current increases. In a photo-cell, the photo current has no relation with the applied voltage.
    ​Stopping potential is the (negative) potential at which the current is just reduced to zero. It is independent of intensity of light but depends on the frequency of light similar to K.E.

  1. The cathode of a photoelectric cell is changed such that the work function changes from W1 to W2 (W2 > W1). If  the current before and after changes are I1 and I2, all other conditions remaining unchanged, then (assuming hν > W2)








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    The work function has no effect on photoelectric current so long as hν > W0. The photoelectric current is proportional to the intensity of incident light. Since there is no change in the intensity of light, hence I1 = I2.

    Correct Option: A

    The work function has no effect on photoelectric current so long as hν > W0. The photoelectric current is proportional to the intensity of incident light. Since there is no change in the intensity of light, hence I1 = I2.