Question

Wavelength of light used in an optical instrument are λ₁ = 4000Å and λ₂ = 5000Å, then ratio of their respective resolving powers (corresponding to λ₁ and λ₂ ) is

(a) 16 : 25 

(b) 9 : 1 

(c) 4 : 5 

(d) 5 : 4.

Answer 1

(d) : Resolving power is proportional to λ^–1

Therefore, (R.P.for λ₁)/(R.P. for λ₂) = λ₁/λ₂ = (5000)/(4000) =5/4.