Write characteristic of photon or How photon of electromagnetic radiation can be represented ? 

From photoelectric effect and Compton effect characteristics of photon can be represented as follows :
$(1)$ During interaction of radiation with matter, radiation behaves as real particle which is called photon.
$(2)$ Energy of each photon is $h \mathrm{v}$ and momentum of each photon is $p=\frac{h \mathrm{v}}{c}$.
$(3)$ In vacuum speed of photon is equal to speed of light $(c)$.
$(4)$ If $\lambda$ is wavelength of radiation and $v$ is frequency of photon then energy of each photon $\mathrm{E}=h \mathrm{v}=\frac{h c}{\lambda}$ and momentum of each photon $p=\frac{h \mathrm{v}}{c}=\frac{h}{\lambda} .$ This is independent of intensity.

$(5)$ According to photon theory if $n$ photons are incident on unit area then intensity of light $\mathrm{I}=$ $n h v$ where $h v=$ energy of 1 photon, $v=$ frequency of incident light. Energy of photon does not depend on intensity of radiation.

$(6)$ Photons are electrically neutral. They do not get deflected by electric or magnetic field.

$(7)$ During photon-particle collision (for example electron-photon collision) of total energy and total momentum are conserved. Some times conservation of number of photons may not take place or new photon may be produced.

$(8)$ Mass of photon $m=\frac{h v}{c^{2}}$

According to Einstein's theory of relativity,

$\mathrm{E}=m c^{2}$

$\therefore h \mathrm{v}=m c^{2}$

$\therefore m=\frac{h \mathrm{v}}{c^{2}}$