Reflection, refraction, and diffraction are all important properties of waves that describe how waves behave when they interact with objects or different materials. Reflection occurs when a wave strikes a surface or object and bounces back. All types of waves, including sound, water, and light waves, can be reflected. For example, an echo is produced when sound waves reflect off a surface. The Law of Reflection states that the angle of incidence (i), or the angle at which a wave hits a surface, is always equal to the angle of reflection (r), or the angle at which it bounces away.

While reflection involves waves bouncing off a surface, refraction occurs when a wave changes speed as it moves from one medium to another, causing the wave to bend. A common example is a pencil appearing bent or broken when placed in water. This happens because light waves travel at different speeds through air and water.

Diffraction also causes waves to bend, but it occurs in a different way. Diffraction happens when waves bend around an object or spread out after passing through an opening. For example, sound waves can travel around corners because they diffract as they move. Although both refraction and diffraction involve bending waves, refraction occurs when waves pass through different materials, while diffraction occurs when waves move around obstacles or through openings.

Waves can also interact with one another through a process called interference. Interference occurs when two or more waves meet at the same place and time, combining to form a new wave. There are two types of interference: constructive and destructive interference. Constructive interference occurs when waves combine to create a wave with a larger amplitude, meaning more energy. Destructive interference occurs when one wave has a positive amplitude, and another has a negative amplitude. As the waves overlap, they partially or completely cancel each other out, producing a smaller amplitude.

Review:

1. What types of waves can be reflected?
2. Explain diffraction.
3. Compare constructive interference to destructive interference.