Waves can behave in several ways as they interact with objects and each other. They can reflect off surfaces, refract as they pass between different materials by changing speed and direction, diffract by bending around barriers, and interfere by combining with other waves to form a new wave. Reflection causes echoes, refraction makes underwater objects look closer, diffraction allows sound to travel around corners, and interference is used in things like CDs and ear plugs.

1. How do waves behave? 7SCIENCE Thurs. May 11

2. Review Where can you find the amplitude on a wave? Distance halfway between the crest and trough What does a high/low amplitude mean? High amplitude = wave has more energy Low amplitude = wave has less energy How do you measure a wavelength? From trough to trough or crest to crest How does wavelength relate to frequency? If a wave has a long wavelength, it will have a low frequency

3. Wave behavior Waves act in many different ways (ex. sound waves and light waves), and may produce a: Reflection Refraction Diffraction Interference

4. Wave behavior:Reflection Echoes: an echo is an example of reflected sound Reflection occurs when a wave strikes an object or surface and bounces off Example: light waves reflect from your face and strike the mirror, bounce off and reflect into your eyes

5. Wave behavior: Refraction Light waves change direction when they are reflected but can also change when passing through a different substance Refraction occurs when a wave bends as it moves from one substance into another Ex: pencil/straw in clear glass of water, fish in water look closer than they really are Waves will speed up or slow down depending on the substance, and bend in different ways

6. Wave behavior: Diffraction Diffraction occurs when waves bend around a barrier Ex: you can hear sound from another room even though you are far away Does light diffract? Ex: you can’t see the people in a room until you are at the door Answer: Light diffracts a small amount because its wavelengths are much shorter than sound and cannot bend easily around corners, like through a door

7. Wave behavior: Interference Interference occurs when two or more waves combine to form a new wave Ex: when many trumpets play the same note at the same time, the waves combine to form a wave with a larger amplitude Ex: light waves experience interference on CDs to produce the many different colors Interference is used in ear plugs, which reflect and absorb some of the harmful sound waves