Understanding Snell’s Law: How Light Bends

Have you ever noticed how a straw looks bent when you put it in a glass of water? That’s similar to what Snell's Law helps us understand about light.

What is Snell’s Law?

Snell’s Law is a formula that helps us predict how light rays change direction when they move into a different material, like water.

The basic idea is this: The way light bends depends on the materials it’s moving between.

Here’s the simple formula we use:

$$n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$$

Let’s break it down:

• $n_1$ is the refractive index of the first material (like air, which is about 1).
• $n_2$ is the refractive index of the second material (like water, which is about 1.33).
• $\theta_1$ is the angle of incidence (the angle the incoming light ray makes with an imaginary line called the normal).
• $\theta_2$ is the angle of refraction (the angle the light ray makes as it bends in the new material).

Let’s See an Example!

Imagine a light ray hits the surface of water at a 30-degree angle. We can use Snell’s Law to find out what happens next.

1. First, we identify our indices:

   • $n_1 = 1$ (for air)
   • $n_2 = 1.33$ (for water)

2. Next, we change our formula to solve for $\theta_2$:

$$\sin(\theta_2) = \frac{n_1 \sin(\theta_1)}{n_2}$$

3. After doing the calculation, you can find out the angle at which the light will travel inside the water.

So, thanks to Snell’s Law, you can easily predict how light behaves when it moves from one material to another!