Mechanical vs EM
Which type of wave must travel through matter?
mechanical waves
Which wave has vibrations perpendicular to the direction of travel?
transverse
What is the highest point of a transverse wave called?
crest
If 10 waves pass a point in 5 seconds, what is the frequency?
2 Hz
Why can sunlight reach Earth through space?
Sunlight is EM and can travel through a vacuum
Name one mechanical wave and one electromagnetic wave.
mechanical: transverse, longitudinal, surface
EM: radio, micro, infrared, visible light, UV, x-ray, gamma
Which wave has compressions and rarefactions?
longitudinal
What is the distance from crest to crest called?
wavelength
If the frequency is 4 Hz and the speed is 8 m/s, what is the wavelength?
2 m
Why can’t sound be heard in outer space?
Sound is mechanical and needs a medium
True/False: Sound can travel through empty space. Explain briefly.
False
Sound is a longitudinal wave (mechanical) and must need a medium to travel through. Space is empty space (a vacuum).
Classify: light, sound in air, wave on a rope.
light: transverse
sound in air: longitudinal
rope wave: transverse
Define amplitude in one sentence.
Amplitude is the height of a wave from rest position to crest (or depth to trough).
A student counts 15 waves in 3 seconds. Find frequency.
5 Hz
What type of wave is used for medical ultrasound?
mechanical (longitudinal - sound waves)
A student hears thunder after seeing lightning. Which wave is mechanical and which is electromagnetic?
lightning - EM waves
thunder - mechanical
A slinky is pushed and pulled to make crowded and spread-out sections. What type of wave is this?
longitudinal wave
Which term matches: “number of waves per second”? What is it measured in?
Frequency; Hertz (Hz)
Compare: Wave A has higher amplitude than Wave B. Which one carries more energy (in general)?
What part of the EM spectrum is commonly used for remote controls?
Infrared waves
Classify each as M or EM: Wi-Fi, ocean waves, ultrasound, sunlight.
Wi-Fi: EM
Ocean waves: mechanical
Ultrasound: mechanical
Sunlight: EM
Ocean surface waves are often taught as transverse at this level. What visible feature in a drawing supports that?
The wave shows crests and troughs moving up/down while traveling forward
Identify two ways to increase the energy of a wave.
Increase amplitude and/or increase frequency
Two waves travel in the same medium. One has higher frequency. What happens to its wavelength?
shorter wavelength
A storm shakes windows. Explain how energy is transferred without the air traveling across the room
Particles vibrate locally and pass energy along without long-distance matter transfer