The speed of light in a transparent plastic whose index of refraction is 1.5 is A) 1.5 × 10⁸ m/s. B) 2 × 10⁸ m/s. C) 3 × 10⁸ m/s. D) 4.5 × 10⁸ m/s.

Question

Quizplus · Accepted Answer

The speed of light in a medium is given by $v = \frac{c}{n}$, where $c$ is the speed of light in vacuum ($3 \times 10^8$ m/s) and $n$ is the index of refraction. For a plastic with $n = 1.5$, $v = \frac{3 \times 10^8 \text{ m/s}}{1.5} = 2 \times 10^8 \text{ m/s}$.

The Speed of Light in a Transparent Plastic Whose Index