Question

If a soap bubble is 115 nm thick, what wavelength is most strongly reflected at the center of the outer surface when illuminated normally by white light? Assume that n = 1.33. Express your answer to three significant figures and include the appropriate units.

Answer 1

Answer:

$611.8$ nm

Explanation:

$n_{oil}$ = Index of refraction of soap bubble  = 1.33

$t$ = thickness of the soap bubble = 115 nm = 115 x 10⁻⁹ m

$\lambda$ = wavelength of light = ?

$m$ = order = 0

For reflection , the necessary condition is

$2 n_{oil} t = (m + 0.5) \lambda$

$2 (1.33)(115\times 10^{-9})= (0 + 0.5) \lambda$

$\lambda = 6.118\times 10^{-7}$

$\lambda = 611.8$ nm