$A$ photoelectric cell is illuminated by a point source of light kept at a distance $d$. If the distance is reduced to $d/2$,then the number of electrons emitted per second will be:

Explain the effect of variation of intensity of incident radiation on photoelectric current.

Two metallic plates $A$ and $B$,each of area $5 \times 10^{-4} \, m^2$,are placed parallel to each other at a separation of $1 \, cm$. Plate $B$ carries a positive charge of $33.7 \, pC$. $A$ monochromatic beam of light,with photons of energy $5 \, eV$ each,starts falling on plate $A$ at $t = 0$,so that $10^{16}$ photons fall on it per square meter per second. Assume that one photoelectron is emitted for every $10^6$ incident photons. Also assume that all the emitted photoelectrons are collected by plate $B$ and the work function of plate $A$ remains constant at $2 \, eV$. The electric field between the plates at the end of $10 \, seconds$ is:

Light of wavelength $4000 Å$ is incident on a sodium surface for which the threshold wavelength of photoelectrons is $5420 Å$. The work function of sodium is (in $eV$)

During a photoelectric effect experiment,which of the following physical quantities depends on the intensity of the incident radiation?

The curves $(a), (b), (c)$ and $(d)$ show the variation between the applied potential difference $(V)$ and the photoelectric current $(i)$,at two different intensities of light $(I_1 > I_2)$. In which figure is the correct variation shown?