Light and Optics
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. In the case of light, it occurs when light bounces off a surface.
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.
2. Refraction
Refraction is the change in direction of a wave due to a change in its speed, typically when it passes through different media. For light, this happens when it moves from one transparent 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 is refracted as it enters the air, changing its direction.
3. Diffraction
Diffraction is the bending of waves around small obstacles and the spreading out of waves past small openings. It is most noticeable with light when it passes through narrow slits or around sharp edges.
Example: When light passes through a narrow slit and creates a pattern of bright and dark fringes on a screen, this is due to diffraction.
4. Interference
Interference occurs when two or more waves overlap to form a new wave pattern. In the case of light, this can result in areas of increased or decreased brightness. Constructive interference adds the waves together, while destructive interference cancels them out.
Example: The colorful patterns seen in soap bubbles or oil slicks are due to interference. Light waves reflecting off the front and back surfaces of the thin film interfere with each other, creating a spectrum of colors.