The light of two different frequencies whose photons have energies $3.8 \,eV$ and $1.4 \,eV$ respectively, illuminate a metallic surface whose work function is $0.6 \,eV$ successively. The ratio of maximum speeds of emitted electrons for the two frequencies respectivly will be

The photoelectric cut-off voltage in a certain experiment is $1.5 \;V. $ What is the maximum kinetic energy of photoelectrons emitted?

Find the number of electrons emitted per second by a $24 \,W$ source of monochromatic light of wavelength $6600 \mathring A$, assuming $3 \%$ efficiency for photoelectric effect (take $h=6.6 \times 10^{-34} \,Js$ ) $S$

A $100 \;W$ sodium lamp radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is $589\; nm$.

$(a)$ What is the energy per photon associated with the sodium light?

$(b)$ At what rate are the photons delivered to the sphere?

Consider figure for photoemission.

How would you reconcile with momentum-conservation ? Note light (photons) have momentum in a different direction than the emitted electrons. 

Wavelength of a $1 \;keV$ photon is $1.24 \times {10^{ - 9}}\;m$. What is the frequency of $1 \;MeV$ photon