Which of the following graphs shows the correct variation of maximum kinetic energy $(E)$ of photoelectrons with the intensity of incident radiation $(I)$?

The work functions for the following metals are given:
$Na: 2.75\;eV; K: 2.30\;eV; Mo: 4.17\;eV; Ni: 5.15\;eV$. Which of these metals will not give photoelectric emission for a radiation of wavelength $3300\,\mathring{A}$ from a $He-Cd$ laser placed $1\;m$ away from the photocell? What happens if the laser is brought nearer and placed $50\;cm$ away?

The work function of a certain metal is $3.31 \times 10^{-19} \,J$. The maximum kinetic energy of photoelectrons emitted by incident radiation of wavelength $5000 \text{ Å}$ is (Given: $h = 6.62 \times 10^{-34} \,J \cdot s$,$c = 3 \times 10^8 \,m/s$,$e = 1.6 \times 10^{-19} \,C$) (in $\text{ eV}$)

When the electromagnetic radiations of frequencies $4 \times 10^{15} \,Hz$ and $6 \times 10^{15} \,Hz$ fall on the same metal in different experiments,the ratio of maximum kinetic energy of electrons liberated is $1: 3$. The threshold frequency for the metal is ............... $\times 10^{15} Hz$.

$A$ metal surface having work function '$W_{0}$' emits photoelectrons when photons of energy '$E$' are incident on it. The electron enters a uniform magnetic field '$B$' in a perpendicular direction and moves in a circular path of radius '$r$'. Then '$r$' is equal to (where '$m$' and '$e$' are the mass and charge of the electron,respectively).

When a point source of monochromatic light is at a distance of $0.2 \ m$ from a photoelectric cell,the stopping potential and saturation photocurrent are $0.6 \ V$ and $18 \ mA$ respectively. If the same source is placed $0.6 \ m$ away from the photoelectric cell,then: