Question

please help me.

I will make as brain list​

Answer 1

We have

μ′μ=λλ′

where, λ and λ′ respectively are the wavelength of the light in air and in glass slab.

μ and μ′ is the refractive index of air and glass slab respectively.

We have μ=1 and μ′=1.5

⟹λ′=1.5600nm=400nm=4000A°

I think the answer is first option ( i) then( iii)