The maximum kinetic energy of photoelectrons emitted from a surface when photons of energy $6 eV$ fall on it is $4 eV$. The stopping potential in volts is

Light of frequency $8 \times 10^{15} \ Hz$ is incident on a substance of photoelectric work function $6.125 \ eV$. The maximum kinetic energy of the emitted photoelectrons is ........... $eV$.

The graph of stopping potential $V_s$ against frequency $\nu$ of incident radiation is plotted for two different metals $X$ and $Y$ as shown in the graph. If $\phi_x$ and $\phi_y$ are the work functions of $X$ and $Y$,respectively,then:

Light of wavelength $3500 \ \mathring A$ is incident on two metals $A$ and $B$. If their work functions are $4.2 \ eV$ and $1.9 \ eV$ respectively,which metal will emit photoelectrons?

The graph of stopping potential $(V_0)$ versus the frequency $(f)$ of incident radiation for the photoelectric effect 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