The curve drawn between the velocity and frequency of a photon in a vacuum will be a

The radiant energy from the Sun incident on the Earth's surface is $2 \ cal/cm^2 \cdot min$. If the average wavelength of solar radiation is $5500 \ \mathring A$,then the number of photons incident per minute on a surface area of $1 \ cm^2$ on the Earth's surface is ............ $(h = 6.6 \times 10^{-34} \ J \cdot s, 1 \ cal = 4.2 \ J)$

If $n_r$ and $n_b$ are the number of photons emitted per second by a red bulb and a blue bulb of equal power respectively,then:

The energy of a photon of visible light with the maximum wavelength in $eV$ is approximately .......

Which of the following phenomena cannot be explained by the wave theory of light?

$A$ situation of population inversion is related to