The light of two different frequencies whose photons have energies $3.8 \, eV$ and $1.4 \, eV$ respectively,illuminate a metallic surface whose work function is $0.6 \, eV$ successively. The ratio of maximum speeds of emitted electrons for the two frequencies respectively will be

Let $K_1$ be the maximum kinetic energy of photoelectrons emitted by light of wavelength $\lambda_1$ and $K_2$ be the maximum kinetic energy corresponding to wavelength $\lambda_2$. If $\lambda_1 = 2\lambda_2$,then:

If the maximum velocity with which an electron can be emitted from a photocell is $4 \times 10^8 \, cm/s$,the stopping potential is ................ $V$ (mass of electron $= 9 \times 10^{-31} \, kg$).

Given below are two statements:
Statement $I$: Stopping potential in photoelectric effect does not depend on the power of the light source.
Statement $II$: For a given metal,the maximum kinetic energy of the photoelectron depends on the wavelength of the incident light.
In the light of the above statements,choose the most appropriate answer from the options given below.

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

The maximum kinetic energy of a photoelectron liberated from the surface of lithium with work function $2.35 \text{ eV}$ by electromagnetic radiation whose electric component varies with time as: $E=a[1+\cos(2 \pi f_1 t)] \cos(2 \pi f_2 t)$ (where $a$ is a constant) is (given $f_1=3.6 \times 10^{15} \text{ Hz}$,$f_2=1.2 \times 10^{15} \text{ Hz}$ and Planck's constant $h=6.6 \times 10^{-34} \text{ Js}$) (in $\text{ eV}$)