UNIT 3

What is a Wave?Definition: A disturbance that transfers energy from place to place.What carries waves? A medium, a medium is the material through which a wave travels. A medium can be a gas, liquid, or solid.

Not all waves require a medium to travel.

Light from the sun travels through empty space.

What causes waves?Waves are created when a source of energy causes a medium to vibrate.A vibration is a repeated back and forth or up and down motion.

Types of waves: Waves are classified according to

how they move.

Transverse waveWaves that move the medium at right angles to the direction in which the waves are traveling.Transverse means across. The highest parts are called crests the lowest parts are called troughs.

Longitudinal WaveMatter vibrates in the same direction as the wave travels.

Example: Slinky

Longitudinal waveThe parts, where the coils are close together are called compressions, the parts where the coils are spread out are called rarefactions.

Combinations of wavesSurface waves are a combination of transverse and longitudinal waves. The waves occur at the surface between water and air.

Draw a Transverse wave and label: crest & trough

Draw a Longitudinal wave: label compression &

rarefaction

Basic Properties of WavesAmplitudeWavelengthFrequencySpeed

Amplitude

Amplitude is the maximum distance the particles of the medium carrying the wave move away from their rest positions.

The farther the medium moves as it vibrates the larger the amplitude of the resulting waves. The greater the amplitude the greater the amount of energy.

Amplitude of transverse waves

The amplitude of a transverse wave is the maximum distance the medium moves up or down from its rest position. You can find the amplitude of a transverse wave by measuring the distance from rest to crest or rest to trough.

Amplitude of a longitudinal wave.

The amplitude of a longitudinal wave is a measure of how compressed or thin the medium becomes.

WavelengthA wave travels a certain distance before it starts to repeat. The distance between two corresponding parts of a wave is its wavelength.Transverse measure from crest to crest or trough to trough.Longitudinal measure from one compression to the next.

FrequencyThe number of complete waves that pass a given point in a certain amount of time.AKA number of vibrations per second.Frequency measured in hertz (Hz).

SpeedThe speed, wavelength, and frequency of a wave are related to each other by a mathematical formula.Speed = wavelength x frequencyFrequency = speed/wavelengthWavelength = speed/frequency

SpeedWaves in different mediums travel at different speeds. However, in a given medium and under the same conditions the speed of the wave is constant.