Question

A thin film soap bubble (n=1.35) is floating in air. If the thickness of the bubble wall is 300nm, which of the following wavelengths of visible light is strongly reflected?

Answer 1

540 nm

Step-by-step explanation:

According to the question,

The refractive index of the soap bubble,
`n=1.35`.

The thickness of the soap bubble wall is,
`t=300 nm`.

Now, for constructive interference of soap bubble.

`2nt=(m+(1)/(2))\lambda`.

Now for first order m=1.

Therfore,

`\lambda =(4)/(3) tn`

Substitute all the variables in the above equation.

`\lambda =(4)/(3) (1.35)(300 nm)`.

Therefore,

`\lambda =540 nm`.

Therefore the visible light wavelength which is strongly reflected is 540 nm.