wave definition: a disturbance that transfers energy from place to place. what carries waves? medium...

WaveDefinition: A disturbance that transfers energy from place to place.What carries waves?

Medium - the material through which a wave travels

A medium can be a gas, liquid, or solid.

Not all waves require a medium to travel!

Mechanical Waves are waves that require a medium.

Electromagnetic Waves travel through empty space and do not require a medium.

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

Lab: Slinkys in ActionUse a slinky to make different types of waves.Notice how the ribbon moves with each different type of wave.

Where did the energy come from to start the wave?

How could you tell the wave carried energy?

Types of waves: Waves are classified according to

how they move.

Transverse Wave

Teacher’s Domain Animation

Use a marker to trace a particles motion as the wave travels through the medium.How does the particle move with respect to the direction of the wave?

Transverse wave (sometimes called a sine

curve or wave)

Waves that move the medium at right angles to the direction in which the waves are traveling is called a transverse wave 3:15min.

Transverse means across. The highest parts are called crests the lowest parts are called troughs.

Draw & Label a Transverse Wave

Compressional or Longitudinal Wave

Matter vibrates in the same direction as the wave travels.Longitudinal discussion 3:36 min

Compressional or Longitudinal wave

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

Teacher’s Domain animation

Draw & Label a

Compressional/Longitudinal Wave

Summary of Waves - NASA Launch Pad Video Clip

Review, Review, Review…What does a wave carry?

How can waves be generated?

Compare and contrast a longitudinal and transverse wave.

Properties of Waves

Basic Properties of WavesAmplitudeWavelengthFrequencySpeed

AmplitudeAmplitude is the maximum (displacement) 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 rarefied the medium becomes.

Same frequencies, same wavelengths, different amplitudes, different energy

What happens to the frequency if you increase your wavelength?

Frequency decreases

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 (cycles) per second.Frequency measured in hertz (Hz) named after Heinrich Hertz who discovered radio waves in 1886.

Frequency Animation

What is the relationship between period and frequency?

Increase the T (period) and the frequency decreases. This is an inverse relationship.

When you change frequency what else do you change? What do you not change?View Illustration

PeriodThe period of a wave is the time for a particle to make one complete cycle.

Pair Share1. Is there a relationship between

wavelength and frequency? What is it?

2. Is there a relationship between frequency and period? What is it?

3. Is there a relationship between amplitude and frequency? What is it?

1. Yes. A decrease in the wavelength increases the frequency and vice versa.

2. Yes. An increase in the frequency will increase the period and vice versa.

3. NO! Putting a lot of energy into a wave will not affect the wavelength, the frequency or the speed of the wave. The energy imparted to a wave will only affect the amplitude of that wave.

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

SpeedWhat can effect the speed of a wave?

Wave speed depends upon the medium through which the wave is moving. Only an alteration in the properties of the medium will cause a change in the speed.

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.

Ways Waves InteractReflectionRefractionDiffractionInterference

ConstructiveDestructive

Standing Waves

ReflectionWhen an object or wave hits a surface through which it cannot pass, it bounces back.

Angle of incidenceAngle of reflection

Examples of reflectionMirrorEchoBall against a wall

Refraction is when a wave moves from one medium

into another medium at an angle, it changes speed as

it enters the second medium which causes it to

bend. The bending of waves due to a change in speed is called refraction.

RefractionThough all waves change speed when they enter a new medium. Bending occurs when one side of the wave enters the new medium before the other side

DiffractionWhen a wave passes a barrier or moves through a hole in a barrier it bends and spreads out.

InterferenceConstructive interference occurs whenever two waves combine to make a wave with a larger amplitude.

Destructive interference when the amplitudes of two waves combine producing a smaller amplitude.

Standing waves:If the incoming wave and the reflected wave combine at the right places the combined wave appears to be standing still.It appears to be standing in one place, even though it is two waves interfering as they pass through each other.Brightstorm video 9:45 min

Nodes and AntinodesNodes: at certain points, destructive interference causes the two waves to combine and produce an amplitude of zero.

Antinodes are the points of maximum energy. The crests and troughs of a standing wave.

Standing wavehttp://www.stmary.ws/

highschool/physics/home/animations3/waves/standingWaves.html

ResonanceMost objects have a natural frequency of vibration. Resonance occurs when vibrations traveling through an object match the object’s natural frequency.An object that is vibrating at its natural frequency absorbs energy from the objects that vibrate at the same frequency. Occurs in music.

ResonanceWatch as you change the wavelength of a tuning fork.How does this relate to resonance?

Basic Quiz on WavesTry this quiz.