Question

Refractive index of a flint glass varies from 1.60 to 1.66 for visible range. Radii of curvature of a thin convex lens are 10 cm and 15 cm. Calculate the chromatic aberration between extreme colours.

Answer 1

Given the refractive indices for extreme colours. As, n_R < n_V 

n_R = 1.60 and n_V = 1.66 

For convex lens, 

R = 10 cm and R₁₀ = -15 cm

= 0.11 

∴ f_V = 11 cm 

∴ Longitudinal chromatic aberration 

= f_V – f_R = 11 – 10 = 1 cm