**What is refraction of light?**

Refraction of light refers to the **change of direction** when light travels from one substance to a **different substance**.

**How will the light change its direction?**

If a light travels from a less dense substance to a denser substance, such as from air to water, the light will slow down. As the light slows down, it will travel towards the normal line.

In a **less dense substance (faster)**, the light travels **away from the normal line**. In a **denser substance (slower)**, the light changes direction **towards the normal line**.

**There is an equation that summarizes this relationship!**

When light travels from air to another substance, use this equation:

**n=sin(i)/sin(r)**

n = refractive index of the substance

i = angle of incidence

r = angle of refraction

**TIPS:**

I. Refractive index is a measure of how fast light travels through the material.

II. Angle of incidence and angle of refraction is always the angle made by the light ray and the normal line!

**Let's look at an example!!**

Calculate the angle of refraction when the angle of incident is 60° and the refractive index of water is 1.33.

**Step 1. **Substitute all the known variables into the equation.

**1.33=sin(60°)/sin(r)**

**Step 2. **Rearrange the equation to solve for r.

**sin(r)=sin(60°)/1.33=0.65**

**Step 3. **Solve for r.

**r=41°**