A thin polymer film ( ) coats a glass plate

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

Problem

A thin polymer film (

n = 1.30

) coats a glass plate. At normal incidence, the film produces a bright reflection for light of wavelength

450\,\text{nm}

in air and a dark reflection for light of wavelength

600\,\text{nm}

in air. What is the smallest possible thickness of the film that satisfies both conditions? (a)

3.00 \times 10^{2}\,\text{nm}

(b)

3.46 \times 10^{2}\,\text{nm}

(c)

2.60 \times 10^{2}\,\text{nm}

(d)

1.73 \times 10^{2}\,\text{nm}