The Energy of Waves!!!!

Students will describe how

waves transfer energy, types

of waves, properties of

waves, and different wave

interactions

Waves Carry Energy

• Energy can be carried away from its source by a wave.

• A source is whatever is creating the energy

-Such as an earthquake

-A fish’s flippers making waves in a pond

-Clapping your hands to create sound waves

Waves Carry EnergyThe material through which the wave

travels does not move with the wave, but simply moves back and forth in place

-Light beams moving through the atmosphere

-Music sounds moving through the classroom

Energy moves through the medium

A medium is what the wave is moving through

-Air would be a medium for light waves or sound waves

-Water would be a medium for surf’n waves

Energy Moves through the Medium

The particles in the medium transfer energy from one to another(Like a bunch of kids in line pushing on each other)

Each particle passes energy on to the surrounding particles

Sound• Sound waves require a medium in

which to travel

• Sound can travel through solids, liquids, and gasses, but not through a vacuum

Mechanical Waves

• Sound is a mechanical-type wave because it requires a medium to move through

• Any type of wave that requires a medium is considered a mechanical wave

Vacuums• A vacuum is like deep outer

space – very few or NO particles

• A vacuum is NOT a medium

Electromagnetic Radiation

• …Or light… or visible light (other names)

• Does not require a medium to travel through

• Can move through space

• How we get light from the sun!!!

• Or stars…!!!

Types of Waves

• Transverse Waves

• Longitudinal Waves

• Combination Waves

Transverse Waves• The particles in a transverse wave

move across or perpendicular to the direction of the wave

• Remember the energy is what the wave is carrying. The medium does not move down with the wave, only across or perpendicular to the wave.

Transverse Waves• Transverse waves is like a rope being

wiggled.

• The bottom portions of the transverse wave form are called troughs

• The top portion of the transverse wave form is called a crest.

Crest

Trough

Longitudinal Waves

The particles in a longitudinal (or also called compression) wave move back and forth or parallel to the direction of the wave.

Longitudinal Waves The portions where the particles are

crowded together are called compressions, the regions where there are less particles are called rarefactions.

What would this look like with the slinky?

Combination Waves

A longitudinal and transverse wave can combine to form a surface wave.

An example would be the waves of the ocean.

Properties of Waves

• Amplitude

• Wavelength

• Frequency

• Speed

Properties of WavesAmplitude

The height of the wave or maximum distance it vibrates from its rest position

Example: turning up the volume and sound-level on your stereo

Properties of Waves

Wavelength-The distance between two crests or two troughs

Properties of WavesFrequency

~The number of complete waves passing a given point in a certain amount of time.

~Count either crests or troughs~Higher frequency relates to higher

energy and shorter wavelength

Why?????

Properties of WavesSpeed

The speed at which a wave travels

Light travels at 3x108 m/s

which is 300,000,000 m/s

Wave Interactions

• Reflection

• Refraction

• Diffraction

• Interference

Wave Interactions

A wave bouncing back-Water waves on the shore-Light reflected in the mirror-Echoes

Reflection

Wave Interactions

• The bending of a wave from one medium to another

• This changes the speed of the wave and the angle at which it enters the new medium

Refraction

Wave Interactions

When waves bend around corners (such as barrier or opening)

Water out of a hose

Opening must be smaller than the wavelength of the wave

Diffraction

Wave Interactions

• When waves overlap

• Constructive interference increases the amplitude (two crests or troughs meet)

• Destructive interference decreases the amplitude (a crest and trough meet)

Inference

Standing Waves

• Interference can also create standing waves

• A stationary pattern– Constructive interference– Destructive interference

Students will describe how

waves transfer energy, types of waves,

properties of waves,

and different wave

interactions