The work function of a metal is $6.825 \ eV$. Its threshold wavelength is approximately: (Given $c = 3 \times 10^8 \ m/s$)

If a photocell is illuminated with a radiation of $1240 \mathring{A}$,the stopping potential is found to be $8 \text{ V}$. Then the work function of the emitter and the threshold wavelength are:

$UV$ light of $4.13 eV$ is incident on a photosensitive metal surface having work function $3.13 eV$. The maximum kinetic energy of ejected photoelectrons will be : (in $eV$)

Two light beams of different frequencies,having energies $1 \ eV$ and $2.5 \ eV$ respectively,are incident on a metal surface with a work function of $0.5 \ eV$. The ratio of the maximum kinetic energies of the emitted photoelectrons is:

When a photosensitive surface is irradiated by light of wavelengths $\lambda_{1}$ and $\lambda_{2}$,the kinetic energies of the emitted photoelectrons are $E_{1}$ and $E_{2}$ respectively. The work function of the photosensitive surface is

Two streams of photons,possessing energies equal to twice and ten times the work function of a metal,are incident on the metal surface successively. The ratio of the maximum velocities of the photoelectrons emitted in the two respective cases is $x:y$. The value of $x$ is ...... .