$A$ metal has a work function of $2.5 eV$. If radiation of frequency $3.2 \times 10^{15} Hz$ is incident on this metal surface,then the maximum kinetic energy of the ejected photoelectrons is (Planck's constant,$h = 6.6 \times 10^{-34} J-s$) (in $eV$)

When the energy of the incident radiation is increased by $20\%$,the kinetic energy of the photoelectrons emitted from a metal surface increases from $0.5\, eV$ to $0.8\, eV$. The work function of the metal is ............. $eV$.

The threshold frequency of a photosensitive material is equal to the frequency of the $H_{\alpha}$ line of hydrogen. If a photon whose frequency is equal to the frequency of the $H_{\beta}$ line of hydrogen is incident on this photosensitive material,the maximum kinetic energy of the emitted photoelectrons is ($R$ = Rydberg's constant,$h$ = Planck's constant,and $c$ = speed of light in vacuum).

If a photocell is illuminated with a radiation of $1240 \mathring{A}$,the stopping potential is found to be $8 \text{ V}$. Then the work function of the emitter and the threshold wavelength are:

If the frequency of light in a photoelectric experiment is doubled,the stopping potential will

An electron moving with velocity $1.6 \times 10^7 \ m/s$ has a wavelength of $0.4 \ \mathring{A}$. The required accelerating voltage for the electron motion is (charge on electron $= 1.6 \times 10^{-19} \ C$,mass of electron $= 9 \times 10^{-31} \ kg$).