1. Sound and Light

2. What is a wave? Disturbance that travels through a medium (substance) When a wave isn’t traveling, it is considered to be in equilibrium position – Imagine a stretched out slinky just sitting on a desk- that’s equilibrium

3. Once a particle moves at the front, the energy of that particle will travel throughout the slinky to the other end. That creates a wave! Waves transfer energy, not particles – This explains why boats sitting in the middle of the ocean can just sit in one spot, and don’t travel with waves

4. What are some types of waves? Based on the Direction of Particle Movement Transverse – Particles move perpendicular to the direction of energy transfer Particles move up and down, but energy is transferred left to right. These are the waves we draw/imagine when we hear the word.

6. Longitudinal – Particles move parallel to the direction of energy transfer Particles move left and right, energy transferred left and right.

8. Based on their Ability to Transfer Energy in Different situations Electromagnetic Waves – Can transfer energy in a vacuum (SPACE!) – Ex: Light waves Mechanical Waves – Cannot transfer energy in a vacuum – Ex: sound

9. What are some parts of waves? Transverse – Crest (High point) – Trough (Low point) Longitudinal – Compression (High pressure) – Rarefaction (Low pressure)

10. Wavelength – Length of one cycle – Ex. Distance from one crest to the next, one trough to the next, one compression to the next, etc. – Units: same as those for DISTANCE (meters- usually with a prefix like nm = nanometer)

12. Amplitude – Displacement of particles from equilibrium (rest) position – Most of the time considered to be from rest to crest or rest to trough – Harder to measure in longitudinal waves – Units: Same as DISTANCE (some form of meters, usually with prefix) – Increased amplitude means louder sound.

13. What do you mean when you talk about the frequency and period of a wave? Frequency – Amount of wave cycles that pass in a certain amount of time – NOT the same as speed of a wave! – Units: HERTZ (cycles per second) – Increased frequency means higher “pitch”

15. Period – The amount of time it takes for one complete cycle – Units: same as for time (seconds, hours, minutes, years, etc) Relationship between the two – As you increase the frequency, the period will decrease – Inversely related

16. – Equation: Frequency (f) = #cycles/period(T) or Period(T)= # cycles /frequency(f) – Units: Frequency is hertz (Hz) and period needs to be in seconds

17. What is the relationship between speed, frequency, and wavelength? Speed is not dependent on wavelength or frequency – Speed IS dependent on the medium of travel – Waves travel fastest through solids and slowest through gases (think of the closeness of particles/ease of energy transfer!)

18. As the wavelength increases: – Waves spread out, so frequency decreases – Wavelength is INVERSELY related to frequency WAVE Equation: velocity (speed) = wavelength x frequency

19. What is the Doppler Effect? When a sound travels toward you and then away from you the change in sound is called the Doppler Effect. Ex. Ambulance passing you: high pitch when traveling toward you, then low pitch when traveling away.Ambulance

22. Due to a perceived change in frequency (notice the number of waves hasn’t changed, but they are just squished into a smaller area)perceived change in frequency

23. What causes a sonic boom? When an object is traveling at the speed of sound, the waves in the front of the object become all bunched up. Then, the object travels faster than the speed of sound. (Supersonic!)

24. Supersonic boom- faster than speed of sound (compressions and rarefactions are heard all at once) – This bunching causes a shock wave – The audio result is a sonic boom- when all the compressions and rarefactions are heard at one timesonic boom- heard at one time

26. Wave Interference What happens when two waves collide? This means two waves are traveling toward each other Called interference

27. 2 Types of Interference Constructive Interference – Colliding waves cause an increase in amplitude, which means a louder sound – Both are above equilibrium line (or in compression) OR both waves are below equilibrium line (or in rarefaction)

29. Destructive Interference – Colliding waves cause a decrease in amplitude, which means a quieter sound (maybe completely cancel out) – One wave is above equilibrium line and other is below equilibrium (or one is in compression, the other is in rarefaction)

31. Waves continue on as if nothing happened (they don’t stop!) Interference is the cause of “beats” when two sounds collide.

33. Wave Interactions Reflection – Wave hits something and bounces back – Causes echoes of sound Refraction – Wave changes speed – With sound, can only happen if medium of travel changes!

34. Diffraction – Wave travels around barriers (ex. Out the door and down the hall)

35. What are electromagnetic waves? Stars, including our sun, emit many types of radiation, which travel to Earth in the form of waves. There are also some man-made waves in Earth’s atmosphere, such as TV waves. These waves are called electromagnetic waves.

36. Types of electromagnetic waves:  Cosmic Rays  Gamma (γ) Rays  X-Rays  Ultraviolet (UV) Radiation  Visible Light  Infrared Radiation  Microwaves  TV Waves  Radio Waves

37. What is the electromagnetic spectrum? The classification of electromagnetic waves, either by wavelength or frequency.

39. Wavelength:The distance between two consecutive crests (tops) of a wave.

40. Frequency:The number of crests that pass any given point during a period of time.

41. What is the difference between the various types of electromagnetic waves? The only difference between the various types of waves is the amount of energy the waves carry: The shorter the wavelength, the higher the energy.