The light reflected from a soap bubble (n = 1.40) appears red ($\lambda$ = 640 nm) at its centre.What is the minimum thickness (in nm)?
A)124
B)104
C)114
D)134
E)234

Question

Quizplus · Accepted Answer

The minimum thickness for constructive interference in a thin film is given by $ t = \frac{\lambda}{4n} $. Substituting the given values, $ t = \frac{640}{4 \times 1.40} = 114 $ nm.

The Light Reflected from a Soap Bubble (N = 1 λ\lambdaλ

The Light Reflected from a Soap Bubble (N = 1 $\lambda$