Characteristics of Waves Chapter 9 S8P4a. Identify the characteristics of electromagnetic and mechanical waves. S8P4d. Describe how the behavior of waves is affected by medium (such as air, water, solids.) S8P4f. Diagram the parts of the wave

The Nature of Waves

1) A wave is any disturbance that transmits energy through matter or space Examples: water waves in the ocean microwaves light waves radio waves sound waves

2) Waves carry energy away from their source, but they DO NOT carry material

3) The substance the wave passes through is called a medium. Sound waves and ocean waves require a medium – they are called mechanical waves.

4) Electromagnetic waves can transfer energy without traveling through a medium. Examples? light, microwaves, TV and radio signals, X-rays

5) Two types of waves: a) transverse b) longitudinal

6) Transverse waves move up and down – particles move perpendicular to the path of the wave

7) In longitudinal waves the particles of the medium vibrate back and forth in the path of the wave

Properties of Waves

1) The amplitude of a wave is its height above the rest position. A larger amplitude means more energy

2) The wavelength is the distance between two crests or two compressions wavelength

3) Frequency: the number of waves produced in a given amount of time; greater frequency means more energy

4) Wave speed – the speed of the wave Wave speed= wavelength X frequency

Wave Interactions Or, What happens when waves hit stuff?

1) Reflection: waves bounce back after hitting something

2) Refraction occurs when waves bend when they pass from one substance to another. Particle and wave refraction/animation

3) Diffraction occurs when waves bend as they pass through an opening or around a corner.

4) Interference occurs when two or more waves overlap. Constructive interference occurs when overlapping waves get bigger.

4b) Destructive interference occurs when overlapping waves get smaller.

5) Standing waves result from interference that creates a stationary pattern of waves.

6) Resonance occurs when one object causes another to vibrate without touching it Tacoma Narrows Bridge Breaking a wine glass using resonance