# Characteristics of Waves Chapter 9 S8P4a. Identify the characteristics of electromagnetic and mechanical waves. S8P4d. Describe how the behavior of waves.

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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 wave motion: a) transverse b) longitudinal

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

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

Reminder: All electromagnetic waves are transverse, but not all transverse waves are electromagnetic Ex: light – electromagnetic + transverse Ocean waves: mechanical and transverse BUT: all longitudinal waves ARE mechanical

Summary point 1: Turn to your neighbor and explain: What do electromagnetic and mechanical waves have in common. What makes mechanical waves different from electromagnetic. Write the answers to both questions in your notes.

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

1) Draw a transverse wave on your paper – label amplitude and wavelength, crest and trough 2) Draw 2 transverse waves on your paper. Make wave A have a high frequency and wave B have a low frequency. Label each.

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.

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. This

4b) Destructive interference occurs when overlapping waves get smaller. This http://phet.color ado.edu/en/simul ation/wave- interference

5) Standing waves result from interference that creates a stationary pattern of waves. http://web.ncf.ca/ch865/frenchdescr/StandingWaveString.html

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

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