Property of Waves
Uploaded by blkbelt121 on Feb 04, 2008
I. What is a wave
A wave is a disturbance that carries energy through matter or space.
II. Most waves travel through a medium
i. sound travels as a wave
a. the air through which sound travels is its medium
ii. earth quakes make waves called seismic waves that travel through earth
a. medium- the matter through which a wave travels
b. waves that require a medium to travel through are called mechanical waves
1. almost all waves are mechanical waves
2. an exception to this is electromagnetic waves
III. Light does not require a medium
i. light can travel from the sun to the earth across the empty space
ii. this is possible because light waves do not need a medium to t ravel through
iii. light waves consist of changing electric and magnetic fields in space
a. electromagnetic waves- a wave caused by a disturbance in electric and magnetic fields and that does not require a medium
IV. Waves transfer energy
i. waves carry energy because they can do work.
ii. Ii. The bigger the wave is, the more energy it carries
a. A cruise ship moving through water in the ocean could create waves big enough to move a fishing boat up and down a few meters.
iii. Tsunami- a huge ocean wave caused by earthquakes
a. A tsunami may be as high as 30 meters when it reaches the shore
1. such waves carry enough energy to cause a lot of damage to costal towns and shore lines
V. Energy may spread out as a wave travels
i. when you are standing next to the speakers at a rock concert, the sound will damage your ears, however if you 100m from them, the sound is not as loud
a. this is because sound waves spread out over a larger area
ii. When sound waves travel in air, the waves spread out in spheres
a. These spheres are similar to the circular ripples on a pond.
1. as they travel outward, the spherical wave fronts get bigger, so the energy in the waves spreads out over a larger area.
2. this is why large speakers and amplifiers are need to fill a concert hall.
VI. Vibrations and Waves
i. when a singer sings a note, the vocal cords in the singer’s throat move back and forth.
a. that motion makes the air in the throat vibrate, creating sound waves that eventually reach your ears.
b. The vibration of the air in your ears causes your eardrums to vibrate
1. the motion the eardrum triggers a series of electrical pulses to your brain, and your brain interprets them as sounds.
ii. most waves are caused by a...