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:

In a photoelectric experiment,the wavelength of the light incident on a metal is changed from $300\, nm$ to $400\, nm$. The decrease in the stopping potential is close to ................ $V$ $\left( \frac{hc}{e} = 1240\, nm \cdot V \right)$

Two identical photocathodes receive light of frequencies $n_1$ and $n_2$. If the velocities of the emitted photoelectrons of mass $m$ are $V_1$ and $V_2$ respectively,then ($h=$ Planck's constant):

Ultraviolet light of wavelength $200 \ nm$ is incident on a freshly polished surface of iron. The work function of the surface is $4.71 \ eV$. What will be the stopping potential in $eV$? $(h = 6.626 \times 10^{-34} \ Js, 1 \ eV = 1.6 \times 10^{-19} \ J, c = 3 \times 10^8 \ m/s)$

When light of a given wavelength is incident on a metallic surface,the minimum potential needed to stop the emitted photoelectrons is $6.0 \ V$. This potential drops to $0.6 \ V$ if another source with wavelength four times that of the first one and intensity half of the first one is used. What are the wavelength of the first source and the work function of the metal,respectively? $\left[\text{Take } hc = 1.24 \times 10^{-6} \ J \ m\right]$

In a photoelectric experiment,a monochromatic light is incident on the emitter plate $E$,as shown in the figure. When switch $S_1$ is closed and switch $S_2$ is open,the photoelectrons strike the collector plate $C$ with a maximum kinetic energy of $1 eV$. If switch $S_1$ is open and switch $S_2$ is closed and the frequency of the incident light is doubled,the photoelectrons strike the collector plate with a maximum kinetic energy of $20 eV$. The threshold wavelength of the emitter plate is (in $Å$)