In solar cells, a silicon solar cell `(mu = 3.5)` is coated with a thin film
of silicon monoxide `SiO (mu = 1.45)` to minimize reflective losses from the surface.
Determine the minimum thickness of SiO that produces the least reflection at a
wavelength of 550nm, near the centre of the visible spectrum. Assume
approximately normal incidence .

Explanation

The reflected light is a minimum when rays 1 and 2 (shown in figure) meet the
condition of destructive interference.