Refraction

Definition

Refraction is the bending of light as it passes from one medium to another with a different refractive index. This occurs due to the change in light's speed in different media.

5 Must Know Facts For Your Next Test

1. The Law of Refraction, also known as Snell's Law, is given by $n_1 \sin \theta_1 = n_2 \sin \theta_2$ where $n$ represents the refractive index and $\theta$ the angle.
2. The refractive index is a dimensionless number that describes how fast light travels through a material compared to vacuum.
3. When light moves from a medium with lower refractive index to higher refractive index, it bends towards the normal line.
4. Critical angle and total internal reflection occur when light moves from a medium with higher refractive index to one with lower refractive index.
5. Dispersion happens because different wavelengths of light are bent by different amounts when passing through materials.

Review Questions

• What is Snell’s Law and how is it mathematically expressed?
• Explain what happens to the direction of light when it passes from air (lower refractive index) into water (higher refractive index).
• Define critical angle and describe its significance in refraction.

Related terms

Snell's Law:

A formula used to describe the relationship between the angles of incidence and refraction, given by $n_1 \sin \theta_1 = n_2 \sin \theta_2$.

Refractive Index:

A dimensionless number that indicates how much the speed of light is reduced inside a medium; defined as $n = c/v$, where $c$ is the speed of light in a vacuum and $v$ is its speed in the material.

Total Internal Reflection:

A phenomenon where all incident light is reflected back into a medium rather than being refracted, occurring when the incident angle exceeds the critical angle.