physics : class12 Photocurrent : Particle Nature of Light : Dual Nature of Matter and Radiation MCQ Questions and Answers
Practice important
Photocurrent
MCQ questions and answers.
Page 1
of
1
|
10
MCQ Questions
1. What is photocurrent?
A.
Current produced due to the flow of photoelectrons
B.
Current produced due to heating of a metal
C.
Current produced due to magnetic induction
D.
Current produced due to chemical reaction
Correct Answer:
Current produced due to the flow of photoelectrons
Explanation:
Photocurrent is the electric current resulting from the flow of photoelectrons emitted from a photosensitive surface.
2. What happens to the photocurrent when the intensity of incident light is increased, while its frequency remains above the threshold frequency?
A.
Photocurrent increases
B.
Photocurrent decreases
C.
Photocurrent becomes zero
D.
Photocurrent remains unchanged in all cases
Correct Answer:
Photocurrent increases
Explanation:
Higher light intensity causes more photoelectrons to be emitted per second, so the photocurrent increases.
3. The maximum photocurrent obtained when all emitted photoelectrons are collected is called:
A.
Saturation current
B.
Dark current
C.
Leakage current
D.
Reverse current
Correct Answer:
Saturation current
Explanation:
Saturation current is the maximum photocurrent reached when the collecting electrode gathers all the emitted photoelectrons.
4. If the intensity of light is increased at a fixed frequency above the threshold frequency, what happens to the saturation current?
A.
It increases
B.
It decreases
C.
It becomes zero
D.
It always remains the same
Correct Answer:
It increases
Explanation:
Increasing intensity increases the number of photoelectrons emitted per second, thereby increasing the saturation current.
5. What is the photocurrent when the frequency of incident light is below the threshold frequency?
A.
Zero
B.
Very large
C.
Equal to the saturation current
D.
Independent of the light intensity
Correct Answer:
Zero
Explanation:
Light with frequency below the threshold frequency cannot emit photoelectrons, so no photocurrent is produced.
6. In a photoelectric cell, photocurrent is measured by connecting a:
A.
Microammeter in the circuit
B.
Voltmeter only across the battery
C.
Thermometer in series
D.
Galvanometer without any circuit
Correct Answer:
Microammeter in the circuit
Explanation:
Photocurrent is usually small, so it is measured using a sensitive current-measuring device such as a microammeter.
7. What is the effect of increasing the positive potential of the collector on the photocurrent, up to saturation?
A.
The photocurrent increases
B.
The photocurrent decreases immediately
C.
The photocurrent becomes zero
D.
The photocurrent changes into heat only
Correct Answer:
The photocurrent increases
Explanation:
A more positive collector attracts more emitted photoelectrons, so the photocurrent increases until saturation is reached.
8. After saturation current is reached, further increasing the positive collector potential causes the photocurrent to:
A.
Remain nearly constant
B.
Become zero
C.
Decrease to half its value
D.
Reverse its direction
Correct Answer:
Remain nearly constant
Explanation:
At saturation, all emitted photoelectrons are already collected, so increasing the collector potential further does not significantly increase the photocurrent.
9. When a reverse potential is applied to the collector in a photoelectric cell, the photocurrent generally:
A.
Decreases
B.
Increases without limit
C.
Remains equal to the saturation current
D.
Becomes independent of the applied potential
Correct Answer:
Decreases
Explanation:
A reverse potential opposes the motion of photoelectrons toward the collector, causing the photocurrent to decrease.
10. At a fixed frequency above the threshold frequency, two light beams have different intensities. The beam with greater intensity produces:
A.
A larger photocurrent
B.
A smaller photocurrent
C.
No photocurrent
D.
The same photocurrent in every situation
Correct Answer:
A larger photocurrent
Explanation:
Greater intensity means more incident photons per second, producing more photoelectrons and hence a larger photocurrent.
Short Questions and Answers
Practice short questions and answers related to
Photocurrent
.
Short questions are currently unavailable for this page.