Question

What is the third smallest non-zero thicknesses (in nm) of soapy water ( n=1.33 ) on Plexiglas (n=1.50) if it appears green (constructively reflecting 520-nm light) when illuminated perpendicularly by white light?

Answer 1

the third non zero thickness is t = 586.466 nm

Step-by-step explanation:

For a constructive interference, the non zero thickness is given by the formula:

`t = (m \lambda)/(2n)`

Where n = 1.33

m = 3

`\lambda = 520 nm = 520 * 10^(-9) m`

`t = (3 * 520 * 10^(-9) )/(2*1.33)`

t = 586.466 * 10⁻⁹ m

the third non zero thickness is t = 586.466 nm