1. 2019 Waves Test Study Guide Review
Check your answers! Test THURSDAY

2. 1. What is a substance through which a wave can travel?
A medium (some type of matter)

3. 2. Sound waves are best reflected off what type of surface?
Smooth, solid surfaces

4. 3. What does the frequency of a sound wave affect?
How many waves pass a point each second
Pitch (sound waves only)

5. 4. What does the medium through which a sound wave travels affect?
The speed of the sound waves
Ex. Sound travels fastest through solids and slowest through gases

6. 5. What do waves transfer?
energy

7. 6. Which type of wave requires a medium?
Mechanical waves

8. 7. What is a section of a longitudinal wave where particles are crowded together called?
Compressions

9. 8. What occurs when the crests of one wave overlap the crests of another wave? What happens to the resulting amplitude?
Constructive Interference if they line up.
The amplitude gets higher
If it is a sound wave, that would mean it gets louder.
Destructive Interference if they DON’T line up.
The amplitude gets lower
If it is a sound wave, that would mean it gets quieter.

10. 9. What is the part of a longitudinal wave where particles are spread out called?
Rarefaction

11. 10. Give examples of a mechanical wave.
Machanical Waves – waves at the beach travel through water (water is the medium)
Music needs air to travel to the ear (the sound waves use air as the medium)

12. 11. What happens to a wave when it is refracted?
It bends as it changes speed when it has to move from one type of matter to another (like liquid to a gas)

13. 12. The amount a wave diffracts depends on what factors?
Wavelength & size of the opening or barrier

14. 13. What happens when white light is refracted?
It bends and separates into a rainbow

15. 14. What formula do you use to calculate frequency
14. What formula do you use to calculate frequency? What are the correct units for frequency?
Frequency = number of waves / amount of time
F = waves/ t
Time should be given in seconds
Your answer should use the units Hertz (Hz)

16. 15. What is the frequency of a sound when 30 waves pass by in 120 seconds?
f=waves/time
f= 30 waves / 120 s
f = 0.25 Hz

17. 16. What is the formula for calculating wave speed (velocity)
16. What is the formula for calculating wave speed (velocity)? What are the correct units for wave speed?
Wave speed = wavelength x frequency
v = λ x f
λ (wavelength) should be given in units of meters (m)
f (frequency) should be given in units of Hertz (Hz)
Your answer of v (speed) should be given in units of m/s

18. 17. What is the speed of a sound that has a frequency of 280 Hertz and a wavelength of 1.5 meters?
V = λ x f
V = 1.5m x 280Hz
V = 420 m/s

19. 18. How are EM waves arranged?
By wavelength & frequency

20. 19. What is the difference between longitudinal and transverse waves?

21. 20. What separates white light into different colors?
Prisms or water droplets

22. 21. Feeling an increase in temperature is the result of the ___absorption__ of infrared waves.

23. 22. Light is most easily transmitted through __transparent__ objects.

24. 23. An EM wave that can cause sunburn is ___ultraviolet__.

25. 24. Light you can see is called ____visible light___.

26. 25. EM waves that can be used to treat cancer are ____gamma rays__.

27. 26. EM waves used to broadcast TV signals are ___radio__.

28. 27. EM waves used in radar are ____microwaves____.

29. 28. EM waves used in airport security devices are __x-rays__.

30. 29. ___Reflection___ is the bouncing back of light, sound, or heat when the ray hits a surface that it doesn’t go through.

31. 30. ___Refraction___ the bending of a wave as it passes at an angle from one substance, or material, to another.

32. 31. ____Diffraction____ the bending of waves around barriers or through openings.

33. 32. Explain how electromagnetic and mechanical waves are different.
Need a medium to travel o
Can be in the form of transverse OR longitudinal
DON’T need a medium to travel on
Can travel through empty space
Are ALL TRANSVERSE

34. 33. What are 3 ways light can interact with matter?
Light can be absorbed, reflected, or transmitted

35. 34. What is the wavelength of Wave A?
Measure from crest to crest (or you could do trough to trough).
The beginning of the arrow is at 1m. The end of the arrow is at 5m.
5 -1= 4meters. DON’T FORGET UNITS! 1 5

36. 35. What is the wavelength of Wave B?
Measure from crest to crest (or you could do trough to trough).
The beginning of the arrow is at 2m. The end of the arrow is at 10m.
10 - 2= 8meters. DON’T FORGET UNITS!

37. 36. What is the amplitude of Wave A?
Find the resting point for line A
Find how far the wave goes above (or below the resting point)
THE RESTING POINT IS AT 0 METERS. THE TOP OF THE CREST IS AT 5 METERS. 5-0=5METERS

38. 37. What is the amplitude of Wave B?
Find the resting point for line B
Find how far the wave goes above (or below the resting point)
THE RESTING POINT IS AT 0 METERS. THE TOP OF THE CREST IS AT 20 METERS. 20 – 0 = 20 METERS

39. 38. Which wave has the greater frequency?
Wave B shows 4 waves in this time period.
Wave A shows 2 waves in this time period.
More waves/sec = higher frequency
Wave B has a higher frequency.

40. 39. On the graph above label the following: crest, trough, resting point, wavelength, amplitude

41. 40. This is an example of
Reflection – the waves are “bouncing off” the surface.

42. Describe how waves move in a longitudinal wave.
Particles move in the same direction that the wave is moving (back and forth)

43. 41. Describe how particles move in a transverse wave.
Particles move perpendicular to the direction the wave is traveling. (up and down)