Question

The photoelectric current(>0) decreases if
a) The frequency of incident radiation decreases below threshold frequency.
b) The exposure time is decreased
c) The intensity of the source of light is decreased
d) None of these

Answer 1

Answer:

Answer is C. Because the saturation current is directly proportional to intensity of light used

Answer 2

Answer:

Photoelectric current decreases if the intensity of the source light decreases.

Therefore, the option (c) is correct.

Explanation:

• Photoelectric effect is the ejection of electrons from the surface of metal when the particular frequency of light strikes on it. The photoelectric current is number of electrons emitted per second.
• The minimum frequency of light which required to cause the photoelectric effect is called threshold frequency. If the frequency of incident radiation decreases below threshold frequency then photoelectric effect will not take place.
• For a fixed intensity of light, photoelectric current does not depend upon the frequency of the incident light.
• Photoelectric current depends upon the number of photoelectrons emitted. Therefore it depends upon the number of photons incident.

So, if the intensity of the source of light will decrease then the photoelectric current will also decrease.