The work function of a metal is $2.3 \text{ eV}$ and the maximum kinetic energy of photoelectrons is $0.3 \text{ eV}$ when a photon is incident on it. Find the wavelength of the incident photon in $\mathring A$.

Ultraviolet light of wavelength $300 \ nm$ and intensity $1.0 \ W/m^2$ is incident on a photosensitive surface. If only $1 \%$ of the incident photons emit photoelectrons,calculate the number of photoelectrons emitted per second from a surface area of $1 \ cm^2$.

Photoemission from a metal surface takes place for frequencies $v_1$ and $v_2$ of incident rays. If the ratio of the maximum kinetic energy of photoelectrons is $1:K$,then the threshold frequency of the metallic surface is

Photoelectric emission is observed from a metallic surface for frequencies $v_1$ and $v_2$ of the incident light rays $(v_1 > v_2)$. If the maximum values of kinetic energy of the photoelectrons emitted in the two cases are in the ratio of $1:k$,then the threshold frequency of the metallic surface is

According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is

When the energy of the incident radiation is increased by $20\%$,the kinetic energy of the photoelectrons emitted from a metal surface increases from $0.5\, eV$ to $0.8\, eV$. The work function of the metal is ............. $eV$.