Question

What is the minimum thickness of a soap bubble film with refractive index 1.38 that results in a constructive interference in the reflected light if this film is illuminated by a beam of light of wavelength 610 nm?

O 111 nm
O 333 nm
O 222 nm
O 444 nm
O 555 nm

Answer 1

The minimum thickness of the soap bubble film for constructive interference is approximately 222 nm. Hence the correct option is c.

To determine the minimum thickness of the soap bubble film that results in constructive interference, we can use the formula for constructive interference in thin films: 2t=mλ/n, where t is the thickness of the film, m is an integer (in this case, we consider m=1 for the first-order interference), λ is the wavelength of light, and n is the refractive index of the medium (in this case, the soap bubble film).

Rearranging the formula for t, we get t=mλ/(2n). Given that the wavelength (λ) is 610 nm, and the refractive index (n) is 1.38, we can substitute these values to find the minimum thickness of the soap bubble film for constructive interference. The calculated thickness is approximately 222 nm. Therefore, a soap bubble film with a thickness of around 222 nm will exhibit constructive interference when illuminated with light of a wavelength of 610 nm. Hence the correct option is c.