Question

Differentiate between spontaneous and stimulated emission.

Answer 1

Sr. no.	Spontaneous emission	Stimulated emission
1.	It happens naturally when an excited atom returns to ground state without external influence.	It requires an incoming photon to trigger the emission of another photon of the same energy, phase, and direction.
2.	Not useful for LASER because it is random in direction and phase.	Very useful for LASER, as it produces coherent, directional, and monochromatic light.
3.	Does not require external electromagnetic stimulus.	Requires external electromagnetic stimulus.
4.	It says spontaneous emission is more probable than stimulated (left column). It also says stimulated is more probable than spontaneous (right column). These are contradictory statements.	In ordinary conditions, spontaneous emission is more probable because atoms in excited states decay naturally. In the presence of a strong external radiation field (like inside a LASER cavity), stimulated emission can dominate and become more probable.