CBSE
Multiple Choice QuestionsAssertion: A photon has no rest mass, yet it carries definite momentum.
Reason: Momemtum of photon is due to its energy and hence its equivalent mass.
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
In photoelectric effect, the electrons are ejected from metals if the incident light has a certain minimum
wavelength
frequency
amplitude
angle of incidence
The dimensional formula of Planck's constant is
[ M L2 T-1 ]
[ M L2 T-2 ]
[ M L0 T2 ]
[ M L T2 ]
Hard X - rays 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
< 124.2 kV
> 124.2 kV
between 60 kV and 70 kV
= 100 kV
Which of the following is matched wrongly?
Oil drop experiment → Millikan
Dual nature of light → de Broglie
Uncertainty principle → Heisenberg
None of these
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
Light with an energy flux of 18 W/cm2 falls on a non-reflecting surface at normal incidence. The pressure exerted on the surface is
2 N/m2
2 × 10-4 N/m2
6 N/m2
6 × 10-4 N/m2
If the kinetic energy of a particle is increased by 16 times, the percentage change in the de Broglie wavelength of the particle is
25 %
75 %
60 %
50 %
Flash light equipped with a new set of batteries, produces bright white light. As the batteries wear out
the light intensity gets reduced with no change in its colour
light colour changes first to yellow and then red with no change in intensity
it stops working suddenly while giving white light
colour changes to red and also intensity gets reduced
Assertion: Stopping potential depends upon the frequency of incident light but is independent of the intensity of the light.
Reason: The maximum kinetic energy of the photoelectrons is proportional to stopping potential.
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.
