Derivation of Einstein’s coefficient relation With the help of Einstein's coefficients you can understand that why do we need stimulated emission for the LASER light, see here and let me know where you faced the problem?
Population inversion and pumping
LASER Introduction
LASER fundamentals are discussed in this video lecture
Gauss’s theorem and Stoke’s theorem (Statement only)
Gauss’s theorem and Stoke’s theorem
Gradient, divergence, curl and their physical interpretation
Gradient, Divergence and Curl are three mathematical operators to understand better the output of mathematical differential equations
