An antireflection coating is to be applied to a glass surface so that reflection is…

PHYSICS · Single correct · A Level · Physics · Waves · Waves

Problem

An antireflection coating is to be applied to a glass surface

(n=1.50)

so that reflection is minimized at a target wavelength

\lambda_0

in air. Which choice for the coating’s refractive index

n_c

and physical thickness

d

will most effectively achieve this goal? (a)

n_c = 1.50

and

d = \dfrac{\lambda_0}{4 n_c}

(b)

n_c

between

1.00

and

1.50

and

d = \dfrac{\lambda_0}{2 n_c}

(c)

n_c

between

1.00

and

1.50

and

d = \dfrac{\lambda_0}{4 n_c}

(d)

n_c > 1.50

and

d = \dfrac{\lambda_0}{4 n_c}