Question

at a particular spot on a soap bubble (n = 1.33), you see green light at 520 nm. if that is from the longest (m = 1) wavelength possible, how thick is the bubble at that point? ? nm

Explanation:

Step1: Recall thin film formula

For constructive interference in a thin film with phase shifts (soap bubble, air-film-air interface, both surfaces have 180° phase shifts, so the path difference condition is $2nt = m\lambda$)

Step2: Rearrange for thickness $t$

$t = \frac{m\lambda}{2n}$

Step3: Substitute given values

$m=1$, $\lambda=520$ nm, $n=1.33$
$t = \frac{1 \times 520}{2 \times 1.33} = \frac{520}{2.66} \approx 97.7$ nm

Answer:

97.7 nm