How do waves behave?7SCIENCE Thurs. May 11

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

Wave behavior

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

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

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

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

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