The relationship between the velocity and frequency of a photon in a vacuum is represented by 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 ............ $(h = 6.6 \times 10^{-34} \ J \cdot s, 1 \ cal = 4.2 \ J)$

The average number of photons emitted per second by a laser of power $6.6 \times 10^{-3} \,W$ producing light of wavelength $600 \,nm$ is (Planck's constant,$h = 6.6 \times 10^{-34} \,J \cdot s$):

When a photon enters glass from air,which one of the following quantities does not change?

The energy of a photon with a wavelength of $\lambda = 4000 \ \mathring{A}$ is equal to ... $eV$.

The momentum of a photon of light of frequency $f$ is . . . . . . .