Question

light of certain colour has2000 waves to millimiter in air .what will be the wavelength of this light in a medium of refractive index 1.25?​

Answer 1

Answer:

Explanation:

(D) 4000 Å

                          λ = wavelength

                             = [(distance) / (no. of waver)]

                             = [(10–3) / (2000)]

                             = 5 × 10–7 m

                             η = 1.25

                   light is moving from air to medium hence λ1 = (λ/η)

                   ∴        λ1 = [(5 × 10–7) / (1.25)] = 4 × 10–7 m

                   i.e.      λ1 = 4000 × 10–10 m = 4000 Å.