Question

Soap bubble interference Light of 690-nm wavelength interferes constructively when reflected from a soap bubble having refractive index 1.33. Determine two possible thicknesses of the soap bubble.

Answer 1

Answer:

The two possible thicknesses of the soap bubble is 129 nm and 389 nm.

Explanation:

Given that,

Wavelength = 690 nm

Refractive index = 1.33

We need to calculate the two possible thicknesses of the soap bubble

Using formula of thickness

$t=\dfrac{(m+\dfrac{1}{2})\lambda}{2n}$

For m = 0,

Put the value into the formula

$t=\dfrac{\dfrac{690\times10^{-9}}{2}}{2\times1.33}$

$t=129\times10^{-9}\ m$

$t=129\ nm$

For m=1,

Put the value into the formula

$t=\dfrac{\dfrac{3\times690\times10^{-9}}{2}}{2\times1.33}$

$t=389\times10^{-9}\ m$

$t=389\ nm$

Hence, The two possible thicknesses of the soap bubble is 129 nm and 389 nm.