Refraction is caused by a. light bouncing off a surface. b. light changing colors as it enters a new medium. c. light changing speed as it enters a new medium. d. two light beams interfering.

When light travels from one medium to another, it may speed up or slow down. This change in speed happens because different materials have different densities. For instance, light travels faster in air than in water. This change in speed is crucial because it affects how light behaves at the boundary between two media.
For example, when light moves from air (less dense) into water (more dense), it slows down. Conversely, when light exits water into air, it speeds up. This speed change is fundamental in understanding light refraction because it's the reason why light bends as it transitions from one medium to another.

The term 'medium' refers to the material through which light travels. Common media include air, water, glass, and vacuum. Each medium has a specific property called the refractive index, which determines how much the light will bend. When light passes from one medium to another, two things happen:

• Change in speed: As discussed, light changes speed based on the density of the new medium.
• Bending of light: This bending phenomenon occurs at the boundary, or interface, of the two media.

Understanding medium transitions helps us predict and explain how light rays behave under different conditions. For example, opticians use this knowledge to design eyeglasses that correct vision by adjusting how light bends when passing through lenses.

Light bending, or refraction, happens because of the change in light speed when moving between different media. The angle at which light enters a new medium affects the degree of bending. This angle is called the angle of incidence. The angle at which light exits into the new medium is the angle of refraction. According to Snell's Law:
Where:
This mathematical relationship helps in predicting the exact amount of bending for a beam of light.
Refraction is evident in everyday life. For example, a straw in a glass of water appears bent at the surface due to refraction. Similarly, lenses in cameras and telescopes use refraction principles to focus light and produce clear images.