The energy of a photon whose frequency is $10^{12} \text{ MHz}$ is:

The momentum of a photon in an $X-$ray beam of $10^{-10} \ m$ wavelength is

The momentum of a photon with a wavelength of $5000\,\mathring{A}$ is:

There are materials which absorb photons of shorter wavelength and emit photons of longer wavelength. Can there be stable substances which absorb photons of larger wavelength and emit light of shorter wavelength?

The relationship between the velocity and frequency of a photon in a vacuum is represented by a ...... .

Two sources of light emit with a power of $200 \ W$. The ratio of the number of photons of visible light emitted per second by each source having wavelengths $300 \ nm$ and $500 \ nm$ respectively,will be: