The energy of a photon is $E = h\nu$ and the momentum of a photon is $p = \frac{h}{\lambda}$. The velocity of the photon is:

The value of Planck's constant is

If $c$ is the velocity of light in free space,the correct statements about photon among the following are:
$A$. The energy of a photon is $E=h v$.
$B$. The velocity of a photon is $c$.
$C$. The momentum of a photon,$p=\frac{h v}{c}$.
$D$. In a photon-electron collision,both total energy and total momentum are conserved.
$E$. Photon possesses positive charge.
Choose the correct answer from the options given below:

According to the modern theory of the nature of light,light has ...

If the wavelength of an $X-ray$ is $0.010 \ \mathring A$,what is its momentum?

The number of photons emitted from a photocell by a source placed at a distance of $0.5 \ m$ is how many times the number of photons emitted by the same source placed at a distance of $1 \ m$?