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 $eV$)

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?

The curve between the work function of a metal $(\phi_o)$ and its temperature $(T)$ will be:

On a photosensitive surface, if the intensity of incident radiation is increased, the stopping potential

$A$ point source causes the photoelectric effect from a small metal plate. Which of the following curves may represent the saturation photocurrent $(I)$ as a function of the distance $(r)$ between the source and the metal?

In a photoelectric experiment,increasing the intensity of incident light :