Question

how is photon formed?

Answer 1

light is made of photon
A photon is produced whenever an electron in a higher-than-normal orbit falls back to its normal orbit. During the fall from high energy to normal energy, the electron emits a photon -- a packet of energy -- with very specific characteristics.

Answer 2

the electron than the higher orbit level comes back to its normal orbit level it produces photon (a packet of energy) with specific characteristics