If a source of power $4\,kW$ produces $10^{20}$ photons/second, the radiation belongs to a part of the spectrum called
$\gamma$ -rays
$X$ -rays
Ultraviolet rays
Microwaves
In photoelectric effect if the intensity of light is doubled then maximum kinetic energy of photoelectrons will become
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?
What is photoelectron ?
The photoelectric effect can be understood on the basis of
The momentum of a photon with energy $20\, eV$ is