Chapter 20 – The Energy of Waves Section 3 – Wave Interactions pp. 584 - 589

TERMS TO LEARN Reflection: the bouncing back of a wave after it hits a barrier Refraction: the bending of a wave as it passes at an angle from one medium to another

TERMS TO LEARN Diffraction: the bending of waves around a barrier or through an opening Interference: a wave interaction that occurs when two or more waves overlap

TERMS TO LEARN Standing wave: a wave that forms a stationary pattern in which parts of the wave do not move and other parts move with a large amplitude

TERMS TO LEARN Resonance: this occurs when an object vibrating at or near a resonant frequency of a second object causes the second object to vibrate Resonant frequency: the frequency at which standing waves are made

REFLECTION The bouncing back of a wave after it strikes a barrier or an object is called reflection. All waves can be reflected.

REFLECTION When light rays from the Sun strike the surface of the moon, they are reflected which allows us to enjoy moonlit nights.

REFLECTION Reflected sound waves are called echoes. Some animals use echolocation to find food or for navigation.

REFRACTION The bending of a wave as it passes at an angle from one medium to another is called refraction. The speed of a wave changes depending on the medium in which it is traveling

REFRACTION When a wave moves from one medium to another, the speed of the wave changes.

DIFFRACTION The bending of waves around a barrier or through an opening is called diffraction. Most of the time waves travel in straight lines.

INTERFERENCE A wave interaction that occurs when two or more waves overlap is called interference. Interference can either be constructive or destructive. Constructive interference increases amplitude; destructive interference decreases amplitude.

INTERFERENCE Interference can create standing waves. A standing wave is a wave that forms a stationary pattern in which parts of the wave are at rest position because of total destructive interference and parts of the wave have large amplitude due to constructive inference.

STRING THING DEMONSTRATION

RESONANCE This occurs when an object vibrating at or near the resonant frequency of a second object causes the second object to vibrate.

RESONANCE