Close your eyes and listen to these sounds. Click Click Click Click Click Click Click

What is sound? Sound is a form of energy that can be heard and travels in waves. When matter vibrates or moves back and forth very quickly, a sound is made. Sound waves can travel through solids, liquids, or gases. Example: When a school bell rings, parts of the bell will vibrate creating sound.

How does the ear work? Sound waves are sent. The outer ear “catches the sound waves”. The middle ear takes the sound waves and “vibrates” the eardrum. The inner ear sends the messages to the brain. Middle Ear Outer Ear Sound Waves Inner Ear The brain puts it together and hooray! You hear your favorite song on the radio.

Sound Travels Sound travels in waves. Sound must travel through matter to be heard. Remember: Matter can be a solid, a liquid, or a gas. A sound is made when things vibrate. Sound travels by sending vibrations through matter.

Sound Travels Through Matter Gases Most of the sounds we hear travel through gases, such as air. Sound waves travel slowly through the air. For example: Sound from a bell, a horn, or an alarm clock travels through the air. http://www.youtube.com/watch?v=Au1NkDy_dkU Liquids Some sounds that we hear travel through water. Sound waves travel a faster through water than through the air. Sonar is the way to use sounds to locate objects under water. What animals use sonar? Solids Some sounds that we hear travel through solids. Sound waves travel very fast through solids. For example: When you hit a drum, it vibrates, then the sound travels through the air, to your ears.

Sound makes the air vibrate. For sound to be heard, sound vibrations must have air or some other kind of matter to travel through. You cannot hear sound in outer space because there is no air or other matter to carry sound vibrations. How do you think astronauts are able to talk each other in outer space?

Sound can also be blocked. THINK: Why do some people wear ear coverings?

Sound Waves Each Sound wave has unique pattern Frequency Wavelength Amplitude

Sound mediums A medium is a material that sound, a form of energy, need to transfer Speed of sound Solid : Fast speed Liquid : Medium speed Gas : Slow Speed Standard Temperature and Pressure = 3.31 x 102 m/s Vacuum : No Sound

Frequency 1) High frequency means more vibrations hitting the ear. 2. Healthy humans can hear from 20 Hz to 20,000 Hz .http://www.youtube.com/watch?v=H-iCZElJ8m0

Pitch Pitch is the highest or lowest sound an object makes. Objects that vibrate slowly, make a low pitch. Example-drum. Objects that vibrate quickly, make a higher pitch. Example-recorder

Amplitude of Sound Volume control Loudness Strength of the wave ( measured in db “decibels”) Energy of the wave

a) Threshold of hearing (0 db) b) Threshold of pain (120 db)

5) Ultrasonic sound has a frequency greater than 20,000 Hz. a) Dogs (up to 35,000 Hz) b) Bats (over 100,000 Hz) c) Medical diagnosis 6) Infrasonic sound has a frequency below 20 Hz; they are felt rather than heard (earthquakes, heavy machinery).

www.teenbuzz.org http://www.youtube.com/watch?v=h5l4Rt4Ol7M

d. The Doppler effect – the change in pitch due to a moving wave source. 1) Objects moving toward you cause a higher pitched sound. 2) Objects moving away cause sound of lower pitch. 3) Used in radar by police and meteorologists and in astronomy.

18. The Doppler Effect is the apparent change in the frequency of a sound caused by the motion of either the listener or the source of the sound. Check WS “it works for bats”

A sound wave is a longitudinal wave which travels in all directions away from the source.

What do you hear? Did you hear something? Maybe the sound you heard was as quiet as your cat licking her paws. Or maybe it was loud, like a siren going by. Sounds are everywhere, and you have two cool parts on your body that let you hear them all: your ears! No matter where we go, sound waves are all around us.

Cover your ears! Some people who work near loud machines wear ear coverings. The coverings block some of the sound vibrations from reaching the ears. The ear coverings protect your ears from the noise. Have you ever covered your ears? Why?

Audiologist An audiologist is a person who tests people’s hearing. They use special machines that make sounds. They also help people who do not hear well. Have you had your hearing tested?

How You Make Sounds We use our vocal cords to make sounds in our throat. When we speak, our vocal cords vibrate. Place your hand on your throat when you talk, and you can feel the vocal cords vibrate.

Loudness or Volume Volume is the loudness or the softness of a sound. Loud sounds use a lot of energy. Soft sounds use a little energy. Example: The harder a drum is hit, the more the drum will vibrate . The more an object vibrates, the louder the sound it makes.

Wave Properties of Light

Essential Question How is light manipulated to cause ABSORPTION REFLECTION REFRACTION And DIFFRACTION?

Reflection occurs when a wave strikes an object and bounces off occurs with all types of waves obeys the Law of Reflection – the angle of incidence is equal to the angle of reflection

Law of Reflection

Refraction When a wave enters a new medium at an angle, one side of the wave changes speed before the other side, causing the wave to bend.

Refraction (cont.) amount of bending depends on the speed of light in both materials the greater the difference between the speeds of light in the two media, the more the light is bent if light slows down as it passes into the new medium, the light is bent towards the normal (an imaginary line drawn perpendicularly through the surface of the material) if light speeds up as it passes into the new medium, the light is bent away from the normal

Refraction (cont.) amount of refraction depends on the wavelength of the light red light is bent the least violet light is bent the most white light can be separated into colors by refraction in a prism

Diffraction bending of light around a barrier or through an opening occurs with all types of waves

Diffraction Website

Interference caused when light waves overlap each other constructive – interact to build up wave destructive – interact to reduce wave occurs in all types of waves white light can be separated into colors by diffraction and interference using a diffraction grating

Polarization Ordinary light has waves that vibrate in all directions A polarizing filters acts as though it has tiny slits in one direction Only some of the light (vibrating in the same way of the “slit”) can pass through a polarized filter Best example of a polarized filter is sunglasses Polarization Website

Reflection Example Complete the figure to the right to show the Law of Reflection.

Refraction Example Complete the path of a light ray as it goes through water, glass, and back into air

Prisms - ROYGBIV Label the colors of the spectrum you observed. What caused the white light to separate into colors?

Copy the organizer on a separate sheet of paper Match the Description to the behavior. (diffraction, reflection, absorption, refraction) Description of Wave Motion 1. Bounces off the surface at the same angle it hit with 2. Travels through material, but at an altered bent angle 3. Travels through the material until it encounters an obstacle or hole, which it bends around 4. Cannot travel all the way through the material