Define a photon.

What is the difference (energy-wise) between x-ray photon and infrared photon.

The kinetic energy of an electrons is equal to the energy of photons. Show that de-Broglie wavelength of this electrons is less than the wavelength associated with a photon.

A hydrogen atom initially in the ground level absorbs a photon, which excites it to the n = 4 level. Determine the wavelength and frequency of photon.

Write down the relation betwen the energy and the momentum of a photon.

Write down the relation between energy and momentum of photon.

Define capacitance of a capacitor. Define the SI unit of capacitance.