Question

Which statement correctly compares the speed of light

Answer 1

Answer: The correct answer is Option D.

Explanation:

Refractive index is defined as the ratio of speed of light in vacuum to the speed of light in medium. It is represented as $\eta$. Speed of light in vacuum is always equal to $3\times 10^8m/s$

Mathematically,

$\eta=\frac{\text{Speed of light in vacuum}}{\text{Speed of light in medium}}$

If the refractive index is more, the speed of light in that medium will be slow and vice-versa.

As, the refractive index of glass is more than the refractive index of space. Hence, the speed of light will be slower in glass.

Therefore, the correct answer is Option D.

Answer 2

The speed of light in glass is slower than the speed of light through space.