Bundle 11 – Waves
1. How does energy travel through a vacuum? Energy travels along Electromagnetic waves
2. What is a wave? A disturbance (traveling oscillation) that travels through a medium from one location
to another location. Give an example of a wave. A musician’s instrument creates waves of sound that
move through the air to your ears.
3. What are the two types of mechanical waves? Longitudinal and Transverse
4. A __transverse__ wave is a wave in which particles of the medium move in a direction perpendicular to
the direction that the wave moves.
5. A __longitudinal wave is a wave in which particles of the medium move in a direction parallel to the
direction that the wave moves.
6.
7. What is a medium? A substance or material that carries the wave. The news media refers to the
various institutions (radio stations, etc.) that carry the news from one location to another. The news
moves through the media. Media carries the news. Give examples. Air (gas), water, solid
8. A wave transports __energy__ and NOT __matter. The particles of the medium (water molecules, slinky
coils, stadium fans) simply vibrate about a fixed position as the pattern of the disturbance moves from
one location to another location.
9. What type of wave does not require a medium to travel through? Electromagnetic wave (light)
10. What is an electromagnetic wave? A wave of electricity and magnetism that travels at the speed of light
(in a vacuum) – fluctuations (disturbances) of electric and magnetic fields that are perpendicular to each
other.
11. What is a vacuum? Absence of air and air pressure
12. How do mechanical and electromagnetic waves differ? Mech. – require medium to transmit energy.
Electromagnetic – does not need medium.
13. Examples of electromagnetic waves are light, radio, UV, microwaves.
14. Use the picture of a wave below to label the following: wavelength, amplitude, crest, trough, and one
complete cycle.
15. What is a wavelength? The distance from any point on a wave to the same point on the next cycle of the
wave (length of one complete cycle). Ex. From crest to crest, from trough to trough.
16. What is amplitude? Wave’s height - the maximum distance above or below normal rest position
(equilibrium).
17. What is frequency? How often something repeats. How often a wave goes up and down or how many
waves pass in a certain amount of time (the number of complete cycles per second).
18.
19. What is a period? The time it takes for one complete cycle (number of seconds per cycle).
20. What is the speed of light? 3x108 m/s
21. What is faster, light or sound? Light travels almost a million times faster than sound ____ How can you
prove it? When lightning strikes a few miles away, we hear the thunder several seconds after we see the
lightning. Echo.
22. What is the formula to calculate the speed of a wave? V = fʎ
23. What is an acoustic wave? Acoustic_ waves allow humans and other animals to hear. A person’s ear
perceives the vibrations of an acoustic wave and interprets it as sound. The outer ear, the visible part, is
shaped like a funnel to collect sound waves and send them into the ear canal, where they hit the ear
drum, which is a tightly stretched piece of skin that vibrates in time with the wave. The eardrum starts a
chain reaction and sends the vibration through three little bones in the middle ear that amplify sound.
24. What interactions are possible when a wave encounter boundaries – object or surface (how do waves
move)? Reflection, Refraction, Interference, Diffraction, Absorption and Resonance.
25. What is diffraction? The process of a wave bending around a corner or passing through an opening.
26. Why can we hear sounds around a corner but not see someone around a corner? Sound waves have
longer wavelengths so they can diffract around corners. Diffraction changes direction and shape of the
wave.
27. What is absorption? Is what happens when the amplitude of a wave gets smaller and smaller as it passes
through a medium. Give an example. The wave energy is transferred to the absorbing material. Theaters
often use heavy curtains to absorb sound waves so the audience cannot hear backstage noise. The tinted
glass or plastic in the lenses of your sunglasses absorbs some of the energy in light waves – you do not
have to squint!
28. What is wave interference? When two waves come in contact with each other.
29. The entire range of electromagnetic waves is called the electromagnetic spectrum that includes radio
waves, microwaves, infrared light, ultraviolet light, X-rays, and gamma rays.
30. What type of electromagnetic waves do cell phones use? Low end of microwave frequencies (no, these
waves won’t cook your food – b/c lower power)
31. It takes 8 minutes for a light wave to travel from the sun to the earth. How does light travel? It radiates
outward in all directions from the source in a straight line through EM waves.
32.
33. When all the colors of the rainbow are combined we see light without any color that we call white light.
Ex. Sun light, light from electric lights. Black is the absence of color – no light waves reflect off of a
surface, all light is absorbed.
34. How do ROY G BIV colors differ? They have different energies, wavelengths and frequencies.
35. What color of visible light is the hottest? __Violet__ Why? High frequency = High energy.
36. How do frequency, wavelengths, and energy change on the EMS spectrum?
37. What is chlorophyll and why is it green? Green pigment – it reflects only green light
38. What is chromatography used for? A physical method to separate a mixture by passing it
through a medium in which components move at different rates.
39. How do you know if light is being reflected or absorbed? Only reflected light can be seen.
40. What is reflection? The process of a wave bouncing off an object. Give an example. Echo – sound waves
reflecting from a distant object or wall. Reflected image in a mirror – light waves.
41. What is refraction? The process of a wave bending as it crosses a boundary between two mediums. Give
an example. Light waves bend when they move from water to air. Rainbow. A pencil in a cup of water.
The lenses in a pair of glasses bend incoming light waves so that an image is correctly focused within the
eye.