  Reciprocity is a fundamental principle follows the time reversal symmetry of
physics. However, many practical applications require breaking time reversal
symmetry, hence, are called nonreciprocal. This article aims at discussing time
reversal symmetry, developing fundamental building block to achieve
nonreciprocity leading to robust analytical model to explain electromagnetic
rotation upon propagation through nonreciprocal medium. Detailed mathematical
derivation is presented for Faraday and Kerr rotation in the presence of
external bias which breaks time reversal symmetry and leads to achieve
nonreciprocal system. We validate our proposed model for conventional
conditions and we compute the Faraday and Kerr rotation from a reported article
using our proposed mathematical model and observed excellent agreement.
