Albert Einstein was awarded the Nobel Prize in Physics for his work on

If the threshold wavelength of light for photoelectric emission to take place from a metal surface is $6250 \ \text{Å}$, then the work function of the metal is (Planck's constant $= 6.6 \times 10^{-34} \ \text{Js}$) (in $\text{eV}$)

Two identical photocathodes receive light of frequencies $v_1$ and $v_2$. If the velocities of the photoelectrons (of mass $m$) coming out are $v_1$ and $v_2$ respectively,then:

The photoelectric threshold wavelength for a metal surface is $6600 \, \mathring{A}$. The work function for this is:

The threshold wavelength for the photoelectric effect on sodium is $5000\;\mathring{A}$. Its work function is:

The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface,having work function $5.01 \, eV$,when ultraviolet light of $200 \, nm$ falls on it,must be ............... $V$.