When photons of energy $8 \times 10^{-19} \ J$ are incident on a photosensitive material,the de Broglie wavelength of the photoelectrons emitted with maximum kinetic energy is $10 \ Å$. The work function of the photosensitive material is nearly (in $eV$)

Radiation of two photon energies,twice and five times the work function of a metal,are incident successively on the metal surface. The ratio of the maximum velocity of photoelectrons emitted in the two cases is:

Light of energy $E$ falls normally on a metal of work function $\frac{E}{3}$. The kinetic energies $K$ of the photoelectrons are

When a certain metal surface is illuminated with light of frequency $v$, the stopping potential for photoelectric current is $V_{0}$. When the same surface is illuminated by light of frequency $\frac{v}{2}$, the stopping potential is $\frac{V_{0}}{4}$. The threshold frequency for photoelectric emission is:

$A$ silver ball is suspended by a string in a vacuum chamber and ultraviolet light of wavelength $200 \ nm$ is incident on it. The maximum potential acquired by the ball,if the work function of silver is $4.7 \ eV$,will be .............. $V$.

For a given surface,the slope of the graph between the frequency of incident light and the stopping potential is .......