The graph between the maximum speed $v_{\text{max}}$ of a photoelectron and frequency $(\nu)$ of the incident radiation,in the photoelectric effect,is correctly represented by:

The work function of a metal is $4.2 \ eV$. Its threshold wavelength will be .......... $ \mathring A $.

Two identical photocathodes receive light of frequencies $f_{1}$ and $f_{2}$ respectively. If the velocities of the photo-electrons emitted are $v_{1}$ and $v_{2}$ respectively,then:

When light of frequencies ${\nu _1}$ and ${\nu _2}$ $({\nu _1} > {\nu _2})$ is incident on a metal surface,the ratio of the maximum kinetic energy of the emitted photoelectrons is $1:k$. What is the threshold frequency of the metal?

The slope of the graph between stopping potential and the frequency of incident radiation for the photoelectric effect is . . . . . . .

Photoelectric emission is observed from a metallic surface for frequencies ${\nu _1}$ and ${\nu _2}$ of the incident light rays $({\nu _1} > {\nu _2})$. 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