JAMB - Physics (2020 - No. 24)

The refractive index of a liquid is 1.5. If the velocity of light in vacuum is 3.0 x 10\(^8ms^{-1}\), the velocity of light in the liquid is

1.5 x 10\(^8ms^{-1}\)

2.0 x 10\(^8ms^{-1}\)

3.0 x 10\(^8ms^{-1}\)

4.5 x 10\(^8ms^{-1}\)

n = \(\frac{\text{speed in air}}{\text{speed in glass}}\)

1.5 = \(\frac{3 \times 10^4}{\text{speed in glass}}\)

Speed in glass = 3 x 10\(^8\)m/s / 1.5

= 2 x 10\(^8\)m/s