The ratio of work functions of two metals is $1:2$. If light of frequencies $f$ and $2f$ are incident on them respectively,what is the ratio of the maximum kinetic energy of the emitted photoelectrons?

When light of wavelength $\lambda$ falls on the emitter of a photocell,the maximum speed of the emitted photoelectrons is $V$. If the incident wavelength is changed to $\frac{2\lambda}{3}$,the maximum speed of the emitted photoelectrons will be:

In the following diagram,if $V_2 > V_1$,then:

The work function of a material is $4.0 \ eV$. The maximum wavelength of light that can cause the emission of photoelectrons from the material is ............ $nm$.

If the threshold wavelength for sodium is $6800 \mathring{A}$,then the work function will be ............. $eV$.

The stopping potential for photoelectrons from a metal surface is $V_{1}$ when monochromatic light of frequency $v_{1}$ is incident on it. The stopping potential becomes $V_{2}$ when monochromatic light of another frequency is incident on the same metal surface. If $h$ is the Planck's constant and $e$ is the charge of an electron, then the frequency of light in the second case is