Question

A sheet of glass (n=1.50) is coated with a 500nm -thick layer of oil (n=1.42).

Part A

For what visible wavelengths of light do the reflected waves interfere constructively? The range of wavelength of visible light is from 380 nm to 750 nm.

Enter your answers numerically separated by commas.

Part B

For what visible wavelengths of light do the reflected waves interfere destructively?

Enter your answers numerically separated by commas.

Answer 1

Part A)

Trial and error for different m values

Apply 2nt = (m + .5)(wavelength)

2(1.42)(500 X 10^-9) = (m +.5)(wavelength)

When m = 0, no valid answer

When m = 1, no valid answer

When m = 2, wavelength = 568 nm

When m = 3, wavelength = 405.7 nm

Part B

Trial and error for different m values

Apply 2nt = (m)(wavelength)

2(1.42)(500 X 10^-9) = (m)(wavelength)

When m = 0, no valid answer

When m = 1, no valid answer

When m = 2, wavelength = 710 nm

When m = 3, wavelength = 473.3 nm

Only two valid solutions for each part