Assertion:  A tube light emits white light. Reason: Emi

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 Multiple Choice QuestionsMultiple Choice Questions

161.

Assertion: The photoelectrons produced by a monochromatic light beam incident on a metal
surface, have a spread in their kinetic energies. 

Reason: The work function of the metal varies as a function of depth from the surface.

  • If both assertion and reason are true and reason is the correct explanation of the assertion

  • If both assertion and reason are true but reason is not the correct explanation of the assertion

  • If assertion is true, but reason is false

  • Both assertion and reason are false statements


162.

Assertion: The energy (E) and momentum (p) of a phoon are related by p = E/c.

Reason: the photon behaves like a particle.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


163.

A leaf which contains only green pigments is illuminated by a  laser light of wavelength  0.6328 μm. It would appear to be

  • brown

  • black

  • red

  • green


164.

A photon of energy 4 eV is incident on a metal surface whose work function is 2 eV. The minimum reverse potential to be applied for stopping the emission of electrons is

  • 2 V

  • 4 V

  • 6 V

  • 8 V


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165.

We wish to see inside an atom. Assuming the atom to have a diameter of  100 pm, this means that one must be able to resolve a width of say 10 pm. If an electron microscope is used, the minimum electron energy required is about

  • 1.5 keV

  • 15 keV

  • 150 keV

  • 1.5 keV


166.

Assertion:  A red object appears dark in the yellow light.

Reason: The red colour is scattered less.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


167.

Assertion:  Photoelectric effect demonstrates the wave nature of light.

Reason: The number of photoelectrons is proportional to the frequency of light

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


168.

If an electron and a photon propagate in the form of waves having the same wavelength, it implies that they have the same

  • energy

  • momentum

  • velocity

  • angular momentum


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169.

Characteristic X-rays are produced due to

  • transfer of momentum in collision of electrons with target atoms

  • transition of electron from higher to lower electrons orbits in an atom

  • heating of the target

  • transfer of energy in collision of electrons with atoms in the target


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170.

Assertion:  A tube light emits white light. 

Reason: Emission of light in a tube takes place at a very high temperature.

  • if both assertion and reason are true and the reason is the correct explanation of the assertion

  • if both assertion and reason are true and the reason is not the correct explanation of the assertion

  • if assertion is true but reason is false

  • if both assertion and reason are false statements


C.

if assertion is true but reason is false

The tube light is nothing but a gas discharge tube, which can emit light of different colours. This colour depends mainly upon the nature of the gas inside the tube and the nature of the glass. For neon gas the colour is bright red and for CO2 it is bluish. Again the fluorescent glow looks yellowish green for soda glass. So it is the nature of the glass and the gas inside the tube which determines the colour of the fluorescent glow. As argon is filled inside a tube light, the colour of the light is white.


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