Answer:
Step-by-step explanation:
The ray of light is passing from high refractive index medium to low refractive index medium so condition for cancellation of reflected light is as follows .
2μt = (2n+1) λ/2
where μ is refractive index of the medium , t is thickness , λ is wavelength of light and n is a integer .
Putting n = 10
2x 2.62 x t = 21 x 520 / 2 nm
5.24 t = 5460 nm
t = 1042 nm
Thickness required to be added
= 1042 - 1036 = 6 nm .