Waves transmit energy but not matter.

What is a wave? A wave is a repeating disturbance or vibration that transfers or moves energy from place to place.

What creates a wave? Waves are created when a source of energy (force) causes a vibration.

What is a vibration (in relation to wave) A vibration is a repeated back-and-forth or up-and-down motion.

How do waves carry energy? Waves carry energy through empty space or through a medium without transporting matter

What is a medium? A medium is a material through which waves can travel. It can be a solid, liquid, or gas

Special note While all waves can transmit energy through a medium, certain waves can also transmit energy through empty space.

About mediums When waves travel through a medium, the particles of the medium are not carried along with the wave.

Mechanical Waves Mechanical waves require the particles of the medium to vibrate in order for energy to be transferred.

Example Water waves, earthquake/seismic waves, sound waves, and the waves that travel down a rope or spring are also mechanical waves

Frequency Frequency is a measure of how many waves pass a point in a certain amount of time. The higher the frequency, the closer the waves are together and the greater the energy carried by the waves will be.

Amplitude Amplitude is a measure of the distance between a line through the middle of a wave and a crest or trough. The greater the force that produces a wave, the greater the amplitude of the wave and the greater the energy carried by the wave.

Amplitude (cont.) In a transverse wave , the higher the wave, the higher the amplitude. In a longitudinal wave, the more crowded the compression, the higher the amplitude. The more spread out the rarefaction, the lower the amplitude.

Sound waves Sound waves, as with all mechanical waves, cannot be transferred or transmitted through empty space (vacuum)

Sounds Sounds with greater amplitude will be louder.

Wavelength Wavelength is a measure of the distance from the crest on one wave to the crest on the very next wave. (the wavelength can be measure from trough to trough). Shorter wavelength are influenced by the frequency.

Wavelength (cont.) A higher frequency causes a shorter wavelength and greater energy.

Wavelength (cont.) In Longitudinal waves, the wavelength is from compression to compression. There is a good picture of this on page 450 in your textbook.

Transverse Wave

Longitudinal Wave Wavelength

Speed of Waves Speed is a measure of the distance a wave travels in an amount of time.

Speed of waves (cont.) The speed of a wave is determined by the type of wave and the nature of the medium.

Speed of wave (cont.) As a wave enters a different medium, the wave’s speed changes. Waves travel at different speeds in different media.

Important vocabulary Vacuum Mechanical Wave Energy Transverse Wave Medium Transmit Matter Frequency Longitudinal Wave