Question:

The frequency of a light wave in a material is 2×10¹⁴ Hz and wavelength is 5000 Å. The refractive index of material will be:

1.33

1.40

3.00

1.50

Using,
Refractive index, μ = c/v
Here, c = 3×10⁸ m/s
v = υλ = 2×10¹⁴ Hz × 5000 × 10⁻¹⁰ m = 1 × 10⁸ m/s
∴ μ = 3×10⁸ m/s / 1 × 10⁸ m/s = 3