$A$ beam of light falls on a metal surface such that photo-electrons are generated. If the power of the light source starts to decrease linearly with time $t$, then the variation of the photocurrent $I$ and the magnitude of the stopping potential $|V|$ with time is best represented by:

When radiation of wavelength $\lambda$ is incident on a metallic surface,the stopping potential is $4.8 \ V$. If the same surface is illuminated with radiation of double the wavelength,then the stopping potential becomes $1.6 \ V$. Then the threshold wavelength for the surface is

In a photoelectric experiment,the collector plate is at $2.0\,V$ with respect to the emitter plate made of copper $(\phi = 4.5\,eV)$. The emitter is illuminated by a source of monochromatic light of wavelength $200\,nm$.

Photoemission from a metal surface takes place for frequencies $v_1$ and $v_2$ of incident rays. If the ratio of the maximum kinetic energy of photoelectrons is $1:K$,then the threshold frequency of the metallic surface is

The work function of a photosensitive metal surface is $\phi$. When a photon of energy $3\phi$ is incident on the surface,a photoelectron with a maximum velocity of $6.6 \times 10^6 \ m/s$ is emitted. If the energy of the incident photon is increased to $9\phi$,the maximum velocity of the emitted photoelectron will be ..........

Given below are two statements:
Statement-$I$: The figure shows the variation of stopping potential $(V_0)$ with frequency $(v)$ for two photosensitive materials $M_1$ and $M_2$. The slope gives the value of $\frac{h}{e}$,where $h$ is Planck's constant and $e$ is the charge of an electron.
Statement-$II$: $M_2$ will emit photoelectrons of greater kinetic energy for incident radiation having the same frequency.
In the light of the above statements,choose the most appropriate answer from the options given below.