If the momentum of a photon is $p$,then its frequency is:

Which scientist discarded the postulate of ether?

$A$ bulb lamp emits light of mean wavelength of $4500 \mathring A$. The lamp is rated at $150 \text{ W}$ and $8 \%$ of the energy appears as emitted light. How many photons are emitted by the lamp per second?

Consider the figure for photoemission. How would you reconcile this with the law of conservation of momentum? Note that light (photons) has momentum in a different direction than the emitted electrons.

The rest mass energy of an electron is $0.54 \, MeV$. If the velocity of the electron is $0.8 \, c$,then the kinetic energy $(K.E.)$ of the electron is .......... $MeV$.

If $E$ and $P$ are the energy and the momentum of a photon respectively,then on reducing the wavelength of the photon: