Waves and Properties of Waves

Physics

Waves

• A disturbance that carries energy through matter or empty space while moving from 1 place to another.

• They propagate.• What do waves carry?– They carry energy, not matter.

What transports a wave’s Energy?

• Substances that waves carry their energy through are Mediums or empty space.

• Ex:– Solids– Liquids– Gases

Wave Pulse

• A short length of a wave.

Mechanical Waves

• Mechanical Waves must always have a medium to travel through or to transfer energy.

• 2 Types-– 1) Transverse Waves– 2) Longitudinal Waves

Transverse Waves• Transverse Waves:– Cause the medium to vibrate perpendicular to the

direction the wave is moving.• Parts:– 1) Crest- The top part of a wave.– 2) Trough- The lowest part of a wave.

• Ex:– A guitar string being plucked– Rock that is thrown into a pond

Wave Diagrams

• Transverse Waves-– http://id.mind.net/~zona/mstm/physics/waves/part

sOfAWave/waveParts.htm

• Longitudinal Waves-– http://www.kettering.edu/~drussell/Demos/waves/

wavemotion.html

– http://www.glenbrook.k12.il.us/gbssci/phys/Class/waves/u10l1c.html

– http://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.html

Longitudinal Waves

• Cause the medium to vibrate parallel to the direction the wave is moving.

• Parts:– Compression- Parts of a wave where the particles

are pushed or compressed together.– Rarefaction- Parts of a wave where the particles

are spread apart.• Ex: Sound

Wave Diagrams

• Transverse Waves-– http://id.mind.net/~zona/mstm/physics/waves/part

sOfAWave/waveParts.htm

• Longitudinal Waves-– http://www.kettering.edu/~drussell/Demos/waves/

wavemotion.html

– http://www.glenbrook.k12.il.us/gbssci/phys/Class/waves/u10l1c.html

– http://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.html

Electromagnetic Waves

• Can travel through both mediums and empty space.

• Ex:– Light– Gamma Rays

Standing Waves

• Waves that are produced when they are confined/trapped between boundaries.

• Cause the waves to interfere with their own reflections.

• Examples:– Sound– Water

Surface Waves

• Type of waves that cause the medium to move in a circle.

• Ex:– Earthquakes– Ocean Waves

Absorption

• A decrease in amplitude of waves as they pass through a material and lose energy.– The waves will disappear.– The energy of the waves are being absorbed by

the material.• Ex:– Sunglasses absorb sunlight.

Absorption

Absorption

Superposition Principle

• States that when 2 or more waves overlap, the wave that formed is the sum of the individual waves.

• http://www.acs.psu.edu/drussell/Demos/superposition/superposition.html

Differences between Sound and Light Waves.

• 1) Sound Waves must have a Medium to travel through and Light Waves can travel through matter and empty space.

• 2) Sound Waves can travel through all substances.

• 3) Light travels Faster than Sound.

Quiz- 5/2/12, 5/3/12

• 1) What is the wavelength of a wave that has a period of 2.95 minutes and a wave speed of 8.90 m/s?

• 2) Which wave behavior (Reflection, Refraction, Diffraction, Absorption) is occurring when a quarter looks closer to the surface of the water when a person is looking at it in a wishing well.

• 3) Draw a wave and label the following parts- Wavelength, Amplitude, Crest, Trough

• 4) Determine the frequency of a wave that has a period of 32.9 seconds.

Quiz- 5/2/12, 5/3/12• 5) What happens to the wavelength of a wave if the

energy of the wave decreases?• 6) What happens to the frequency of a wave if the

wavelength of the wave gets shorter (decreases)?• 7) Determine the wave speed of a wave that has a

period of 1.35 minutes and a wavelength of 0.56 m.• 8) 2 waves come together and form a single, larger wave

for a moment is an example of _____________________.• 9) How are electromagnetic and mechanical waves

different?• 10) Determine the period of a wave that has a

wavelength of 0.05 and a wave speed of 4.78 m/s.