Assertion : The phtoelectrons produced by a monochromatic light beam incident on a metal surface have a spread in their kinetic energies.
Reason : The work function of the metal is its characteristics property.

Monochromatic light of frequency $6.0 \times 10^{14} \;Hz$ is produced by a laser. The power emitted is $2.0 \times 10^{-3} \;W$.

$(a)$ What is the energy of a photon in the light beam?

$(b)$ How many photons per second, on an average, are emitted by the source?

A hydrogen atom initially in the ground level absorbs a photon, which excites it to the $n = 4$ level. Determine the wavelength and frequency of photon.

The photoelectric effect can be understood on the basis of

An electron and a photon have same wavelength of $10^{-9} \,m$. If $E$ is the energy of the photon and $p$ is the momentum of the electron, then the magnitude of $E / p$ (in $SI$ unit) is