Refractive Index And Electromagnetic Properties — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Refractive Index and Electromagnetic Properties Relates the speed of electromagnetic waves in a medium to the electromagnetic constants of that medium. Speed of light in vacuum c = 1/sqrt(mu 0 epsilon 0) Speed of light in medium v = 1/sqrt(mu epsilon) Definition of n = c/v Substitute c and v to get n = sqrt((mu epsilon)/(mu 0 epsilon 0)) Use definitions epsilon r = epsilon/epsilon 0 and mu r = mu/mu 0 Medium must be linear and isotropic Medium is usually assumed to be non-conducting Valid for non-dispersive media Thinking refractive index only depends on density; it is actually defined by electromagnetic properties. Ignoring relative permeability (though often 1, it is essential for magnetic materials).