List five things that you know about waves. Bell Ringer 4-26-10 List five things that you know about waves.

Chapter 15.1 Waves

A wave is a disturbance that transfers energy from place to place. Remember: Energy is the ability to do work. A medium is the material through which a wave travels. Energy is required to make a wave.

Mechanical Waves Waves that require a medium to travel through are called mechanical waves. They are produced when a source of energy causes a medium to vibrate. A vibration is a repeated back-and-forth or up-and-down motion. Examples of mechanical waves: Water waves Sound waves

Mechanical waves are classified by how they move. Two Types: Transverse Waves Longitudinal Waves

Types Of Mechanical Waves 1. Transverse wave - A transverse wave is a wave in which the motion of the medium is perpendicular to the motion of the wave. For example: The motion of the medium is up and down and the motion of the wave is to the right or left.  Ex: Water waves- The water moves up and down while the wave travels over the surface of the water.

Crest- the high part of a transverse wave Trough- the low part of a transverse wave

Types Of Mechanical Waves 2. Longitudinal wave - A longitudinal wave is a wave in which the motion of the medium is parallel to the motion of the wave. For example; the motion of the medium is left and right and the motion of the wave is to the left or to the right. Ex: sound waves- The air vibrates back and forth along the same direction as the wave is traveling. Ex: a spring in a toy

Compression- parts of the coils that are close together Rarefactions- parts of the coils that are spread out, or rarified.

Electromagnetic Waves A medium is not needed. Ex. waves travel through vacuum. Disturbance of electric and magnetic fields travelling through space. All electromagnetic waves are transverse waves. X-rays, radio waves, and microwaves examples

Electromagnetic Spectrum (p. 578)

Electromagnetic Spectrum Rabbits Mate in Very Unusual and Expensive Gardens

What are electromagnetic waves? Examples: Light, microwaves, x-rays, TV, and radio transmissions They are all the same kind of wave disturbance that repeats itself over a distance called the wavelength.

Radio waves Radio: This is the same kind of energy that radio stations emit into the air in order for you to listen to radios at home or in the car. But radio waves are also emitted by other things ... such as stars and gases in space.

Microwaves Microwaves: they will cook your popcorn in just a few minutes! In space, microwaves are used to learn about the structure of nearby galaxies, including our own Milky Way!

Infrared: we often think of this as being the same thing as 'heat', because it makes our skin feel warm. Visible: yes, this is the part that our eyes see. Visible radiation is emitted by everything from fireflies to light bulbs to stars ... also by fast-moving particles hitting other particles. Ultraviolet: we know that the Sun is a source of ultraviolet (or UV) radiation, because it is the UV rays that cause our skin to burn! Stars and other "hot" objects in space emit UV radiation.

X-rays: your doctor uses them to look at your bones and your dentist to look at your teeth. Hot gases in the Universe also emit X-rays . Gamma-rays: radioactive materials (some natural and others made by man in things like nuclear power plants) can emit gamma-rays. Big particle accelerators that scientists use to help them understand what matter is made of can sometimes generate gamma-rays. But the biggest gamma-ray generator of all is the Universe! It makes gamma radiation in all kinds of ways.