Advanced Physical Science Lockwood 2012

You and your family have just returned home from a day at the beach. You had fun, but you are hungry from playing in the ocean under the hot sun. You put some leftover pizza in the microwave for dinner, and you turn on the radio. Just then, the phone rings. It’s your best friend calling to find out if you’ve done your math HW yet. How many different waves are present? At least 5

What is a wave? A disturbance that transmits energy through matter or space Energy travels in a wave, but the matter does not move from place to place. All waves are produced by vibrations.

How do waves travel? Some waves transfer energy by the vibration of particles in a medium Medium-the matter through which waves travel Can be solid, liquid, gas, or a combination of both Sound travels best in a solid Ocean waves travel in water

Not all waves need a medium - example: electromagnetic waves- light, radio, heat Waves that must travel through a medium are called mechanical waves Electromagnetic waves do not require a medium.

Types of Waves: Transverse Waves Up and down motion Move in right angles to the direction they travel Like moving a rope up and down Examples: Guitar string Light Transverse Waves

Types of Waves: Compression Waves Matter in the medium moves in the same direction as the wave motion. Think…Slinky! Also called longitudinal waves. Example: Sound waves Two major parts : Compressions & Rarefactions Compressions: where waves squeeze together Rarefactions: where waves pull apart Compression Wave

Types of Waves Surface waves are a combination of longitudinal and transverse waves Seismic waves are an example

Characteristics of Waves Words to know: Trough Crest Amplitude Wavelength crest trough

More about characteristics Amplitude: Height of the wave Energy carried by the wave Related to the loudness of sound and the brightness of light Velocity: Speed of the wave Light travels at 300,000,000 m/s (3.0 x 10 8 ) Speed of sound varies with the medium Speed in air: 340 m/s Speed in water: 1450 m/s Frequency: Rate at which crests pass a given point Cycles per second

And now for the math… Frequency Measured in Hz (cycles / second) What’s that weird symbol??? That’s the Greek letter, lambda Represents the wavelength Velocity Measured in meters/second Same formula…rearranged!

Electromagnetic Spectrum The electromagnetic spectrum is a map of all the types of light that we can identify. Separates all the types of light by wavelength because that directly relates to how energetic the wave is. More energetic waves have shorter wavelengths while less energetic waves have longer wavelengths. Not all light is in the visible spectrum, which is the light you can see. There are many kinds of electromagnetic waves that you can't see.

Electromagnetic Spectrum

Visible light is a small part of the spectrum ROYGBIV – Colors in order from longest wavelength to shortest