Question

A parallel air film is formed between two glass plates.
If the film thickness is 0.45 x 10-6m, the film will be best
reflector for visible light in the neighbourhood of
(a) 9900 À
(b) 6750 Å
Lo 6000 Å
(d) 4500 Å​

Answer 1

$</p><p>(a) 9900 \: À</p><p> </p><p>$

Answer 2

Answer:

given = thickness = 0.45 X 10⁻⁶m

to find =  visible light /wavelength

solution =

apply the formula ,

2μt  =  λ / 2 =  nλ

2μt  =  (2n - 1 )  λ/2

λ = 4μt / (2n - 1)

put the given values ,

λ =  4 X 1 X 0.45 X 10⁻⁶ / (2n - 1)

λ =  1800 / (2n - 1)

we have 2 glass n = 2

λ = 1800 / ( 2 X 2 - 1 )

λ = 6000A°

so the option C is correct answer.