Two light beams of different frequencies,having energies $1 \ eV$ and $2.5 \ eV$ respectively,are incident on a metal surface with a work function of $0.5 \ eV$. The ratio of the maximum kinetic energies of the emitted photoelectrons is:

At an incident radiation frequency of $v_1$,which is greater than the threshold frequency,the stopping potential for a certain metal is $V_1$. At frequency $2 v_1$,the stopping potential is $3 V_1$. If the stopping potential at frequency $4 v_1$ is $n V_1$,then $n$ is

In the case of photoelectric emission from a certain metal,the cutoff frequency is $v$. If radiation of frequency $2v$ is incident on the metal plate,the maximum possible velocity of the emitted electrons will be ($m=$ mass of electron).

When a metallic surface is illuminated with light of wavelength $\lambda$,the stopping potential is $V$. When the same surface is illuminated by light of wavelength $2 \lambda$,the stopping potential is $\frac{V}{3}$. The threshold wavelength for the metallic surface is:

The photoelectric cut-off voltage in a certain experiment is $1.5 \text{ V}$. The maximum kinetic energy of photoelectrons emitted will be . . . . . . .

In a photoelectric experiment, the wavelength of the light incident on the metal is changed from $200 \, nm$ to $400 \, nm$. The decrease in the stopping potential is close to [Use $hc = 1240 \, eV \cdot nm$ where $h$ is Planck's constant and $c$ is the velocity of light]. (in $ \, V$)