Properties of Light
1. Reflection
Reflection is the change in direction of a wavefront at an interface between two different media, so that the wavefront returns into the medium from which it originated. When light hits a smooth surface, it reflects at the same angle it arrived, known as the angle of incidence.
Example: When you look into a mirror, the light from your face hits the mirror and reflects back to your eyes, allowing you to see your reflection. The angle at which the light hits the mirror is equal to the angle at which it reflects off the mirror.
2. Refraction
Refraction is the change in direction of a wave due to a change in its speed. This phenomenon occurs when waves travel from one medium to another where its speed is different. Light bends when it passes from one medium to another, such as from air to water.
Example: When you put a straw in a glass of water, it appears bent. This is because the light traveling through the water and air changes speed, causing it to bend at the boundary between the two mediums.
3. Diffraction
Diffraction is the bending of waves around small obstacles and the spreading out of waves past small openings. This property is more pronounced for waves with shorter wavelengths, such as light. Diffraction causes light to spread out when it passes through narrow slits or around small objects.
Example: When you shine a laser pointer through a small slit, the light spreads out into a pattern of bright and dark fringes on a screen. This pattern is a result of the diffraction of light as it passes through the narrow opening.
4. Interference
Interference is the phenomenon that occurs when two or more waves meet and combine to form a new wave. This can result in either constructive interference, where the amplitudes of the waves add together, or destructive interference, where the amplitudes cancel each other out. Interference is a key property of light waves.
Example: In a double-slit experiment, light passing through two narrow slits interferes with itself, creating a pattern of bright and dark bands on a screen. The bright bands are areas of constructive interference, while the dark bands are areas of destructive interference.