# Light is travelling in water, which has an index of refraction of 1.333. How fast does light travel in water?

Apr 4, 2018

$2.25 \cdot {10}^{8} \setminus \text{m/s}$

#### Explanation:

We use the refractive index equation, which states that

$n = \frac{c}{v}$

• $c$ is the speed of light in a vacuum

• $v$ is the speed of light through the medium

An dso,

$1.333 = \frac{3 \cdot {10}^{8} \setminus \text{m/s}}{v}$

$v = \frac{3 \cdot {10}^{8} \setminus \text{m/s}}{1.333}$

$\approx 2.25 \cdot {10}^{8} \setminus \text{m/s}$