The speed of light decreases.

Total internal reflection occurs; the light is completely reflected back into the original medium.

The light passes straight through without bending (no refraction).

The light slows down and bends towards the normal.

The angle of refraction increases, bending away from the normal.

Refraction: Light bends and enters a new medium. | Total Internal Reflection: Light is completely reflected back into the original medium.

Higher Index: Light bends towards the normal, speed decreases. | Lower Index: Light bends away from the normal, speed increases (if total internal reflection doesn't occur).

Angle of Incidence: The angle between the incident ray and the normal. | Angle of Refraction: The angle between the refracted ray and the normal.

Air: Light travels nearly at its vacuum speed (approximately 3 × 10⁸ m/s). | Glass: Light travels slower than in air, typically about 2 × 10⁸ m/s (depending on the glass).

Reflection: Light bounces off a surface, remaining in the same medium. | Refraction: Light bends as it passes through a surface into a new medium.

The bending of light as it passes from one medium to another due to a change in speed.

A measure of how much light slows down in a medium compared to its speed in a vacuum, calculated as $n = \frac{c}{v}$ .

A law describing the relationship between the angles of incidence and refraction, and the indices of refraction of two media: $n_1 sin \theta_1 = n_2 sin \theta_2$.

The phenomenon where light is completely reflected back into the original medium when attempting to pass into a medium with a lower index of refraction at an angle greater than the critical angle.

The angle of incidence beyond which total internal reflection occurs, calculated as: $\theta_{\text{critical}} = \sin^{-1}\left(\frac{n_2}{n_1}\right)$.