Physics

Problem

Which statement correctly describes the refractive index

n_{\text{coat}}

required for a single-layer antireflection coating applied to a glass lens (

n_{\text{sub}} = 1.52

) that is used in air (

n_{\text{air}} = 1.00

)? a)

n_{\text{coat}}

must be equal to the arithmetic mean

\bigl(n_{\text{air}}+n_{\text{sub}}\bigr)/2

. b)

n_{\text{coat}}

must lie between

n_{\text{air}}

and

n_{\text{sub}}

. c)

n_{\text{coat}}

must be equal to

n_{\text{sub}}

. d)

n_{\text{coat}}

must be smaller than both

n_{\text{air}}

and

n_{\text{sub}}