(a) For normal incidence the reflection coefficient, R, at the planar surface between two dielectric media is given by R=(n1-n2)^2/(n1+n2)^2 where n1 and n2 are the refractive indices of the media. Sketch the form of R against n1 /n2 . On the same figure sketch the form of T against n1 /n2 where T is the transmission coefficient. Indicate numerical values of T and R where appropriate. (b) At what value of n1/n2 does R = T ?