$10^{-3} \, W$ of $5000 \, \mathring{A}$ light is directed on a photoelectric cell. If the current in the cell is $0.16 \, \mu A$,the percentage of incident photons which produce photoelectrons is .......$\%$

$A$ convex lens of focal length $40 \ cm$ forms an image of an extended source of light on a photoelectric cell. $A$ current $I$ is produced. The lens is replaced by another convex lens having the same diameter but focal length $20 \ cm$. The photoelectric current now is:

Write the characteristics of the photoelectric effect.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A :$ In photoelectric effect,on increasing the intensity of incident light,the stopping potential increases.
Reason $R :$ Increase in intensity of light increases the rate of photoelectrons emitted,provided the frequency of incident light is greater than threshold frequency.
In the light of the above statements,choose the correct answer from the options given below:

The following graph represents the variation of photocurrent with anode potential for a metal surface. Here $I_{1}, I_{2}$ and $I_{3}$ represent intensities and $\gamma_{1}, \gamma_{2}, \gamma_{3}$ represent frequencies for curves $1, 2$ and $3$ respectively,then

Which of the following shows the particle nature of light?