The absolute refractive index of water is 1.33. Taking the velocity of light in vacuum as 3 x 10^8 m/s, what is the velocity of light in water?

1. Absolute refractive index n = (velocity in vacuum) / (velocity in medium) = v_1 / v_2. 2. Substitute: $1.33 = \dfrac{3 \times 10^8}{v_2}$. 3. Rearrange: $v_2 = \dfrac{3 \times 10^8}{1.33}$. 4. Compute: $v_2 = 2.26 \times 10^8$ m/s. 5. The option 3.99 x 10^8 wrongly multiplies instead of dividing, so it is rejected; 3.00 x 10^8 ignores the medium entirely. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 6 "Refraction of Light", p.88_