Physics

Problem

Derive an expression for the refractive index

n_{\text{film}}

of an ideal single-layer coating that will eliminate reflected light at normal incidence when deposited on a substrate of index

n_{\text{sub}}

, with air (

n_{\text{air}}\approx1.00

) on the other side. Express your result in terms of

n_{\text{air}}

and

n_{\text{sub}}