1.What causes waves (in general)? What do waves transfer? Waves are caused by vibrations Pulse = single vibration Oscillation – repeating vibration ENERGY.

1. What causes waves (in general)? What do waves transfer?

•Waves are caused by vibrations• Pulse = single vibration• Oscillation – repeating vibration• ENERGY

2. What does the period of a pendulum depend on?

• The period (T) of a simple pendulum depends on:

(1) length of the pendulum(2) acceleration due to gravity

• It is NOT affected by the mass

3. Label the parts of the waves:

TRANSVERSE WAVE

CREST WAVELENGTH (λ)

AMPLITUDE TROUGHEXAMPLE: LIGHT

3. Label the parts of the waves:

LONGITUDINAL WAVECOMPRESSION RAREFRACTION

EXAMPLE: SOUND

WAVELENGTH (λ)

4. Do longitudinal waves require a medium though which to travel? Do transverse waves?

• Longitudinal waves DO require a medium.• Transverse waves DO NOT.

5. What is the unit of measure of a wavelength?

•Meters (m)

6. If the amplitude of a wave is 5 m, how much is the top-to-bottom disturbance?

• 10 m• Amplitude of crest (5 m) plus the

amplitude of the trough (5 m).

7. As waves dissipate what happens to the wave’s amplitude?

• Amplitude decreases as the wave’s energy dissipates/turns into heat.

8. What does frequency tell you? What is the unit of frequency?

• The number of waves that pass a given point in a period of time (usually 1 second).• The unit is the Hertz (Hz)

9. What is interference? What type of interference occurs when waves are in phase? Out of phase?

• Interference is occurrence of multiple waves in the same place at the same time.• Waves in phase exhibit constructive

interference / waves out of phase exhibit destructive interference.

10. What causes the Doppler effect and when does it occur?

• The Doppler effect is the observed shift in frequency caused by motion – either the source or the observer.• It occurs when objects move at a

rate less than the speed of sound.

11. What is the equation for wave speed? What are the units for wave speed?• v = λ x f• Units are meters/second (m/s)

12. If a wave has a wavelength of 20 meters and a frequency of 0.5 Hz, what is speed?

G U E S S

λ = 20 mf = 0.5 Hz v = ? v = (20 m)(0.5 Hz) 10 m/s

13. Does the speed of light change in a vacuum? What is the speed of light in a vacuum?

• NO• The speed of light (c) = 3.00x108 m/s

14. Light travels fastest through which phase of matter? Why is this?

• Air, because the molecules in the air are the most spread out, therefore slowing light down less.

15. How does the speed of light change when going from a gas to a liquid to a solid?

• Light slows down when going from gas to liquid, and from liquid to solid (and vice versa).

16. If a beam of light leaves water and moves into air, how is the beam bent?

• As light speeds up when entering the air, the angle is bent away from the normal.• When moving from air into water

(the reverse), the angle is bent toward the normal.

17. What is reflection?

• When a wave bounces off a material & goes in a new direction.

18. What is refraction?

• When a waves passes through a material & bends.

19. What is diffraction?

• When a wave bends around or passes through an opening in a material.• When plane waves go through an

opening, they become circular waves

20. What is an echo and what property of waves is responsible for it (reflection, refraction, diffraction)?

• An echo occurs when a sound wave reflects off a distant surface / the observer hears the sound wave returning.

21. What causes a rainbow?

• Refraction of visible (white) light through a prism (in nature, rain droplets in the air)

22. List all components of the elecromagnetic (EM) spectrum from lowest frequency to highest.

23. If a light ray strikes a flat mirror at a given angle, at what angle will the reflected ray be?

• An equal angle on the opposite side of the normal.• If the angle of

incidence () is 39°, the angle of reflection () is ___39°___.

24. What is a virtual image and how does it differ from a real image?

• A virtual image is seen in the mirror (behind the mirror) – light rays DO NOT actually come together.• A real image is seen reflected back

out of the mirror.

25. Which type(s) of mirror(s) form a real image? Which form a virtual image?

• REAL – Concave mirror (when object is behind the focal point)• VIRTUAL – Plane mirrors, Convex

mirrors, & Concave mirrors (when object is in front of the focal point).

26. When you look at a flat mirror, how do you see your image?

• VIRTUAL & UPRIGHT

27. When looking at a flat mirror from a distance of X m, your reflected image appears to be how far away from the mirror? How far is it from you?

• Reflected image is X m away from the mirror.• The distance from you is 2X m.

28. Why are ray diagrams used?

• Ray diagrams are used to find out where an image will be located.

29. What is the difference between red and blue light?

• frequency (wavelength)

30. Plane Mirror

p q

RAY 1

• VIRTUAL• UPRIGHT• SAME SIZE

31. Concave Mirror – Behind Focal Point

c f

RAY 1RAY 2RAY 3

• REAL• INVERTED• SMALLER

32. Concave Mirror – In Front of Focal Point

c f

RAY 1RAY 2RAY 3

• VIRTUAL• UPRIGHT• LARGER

33. Convex Mirror

cf

RAY 1RAY 2RAY 3

• VIRTUAL• UPRIGHT• SMALLER

34. Converging Lens

f f

RAY 1RAY 2RAY 3

• INVERTED• SAME SIZE

35. Diverging Lens

f f

RAY 1RAY 2RAY 3

• REAL• UPRIGHT• SMALLER

36. The lowest pitch that the average human can hear has a frequency of 20.0 Hz. If sound with this frequency travels through air with a speed of 331 m/s, what is its wavelength?

G f = 20.0 Hz v = 331 m/s

U λ = ?E λ = v / f

S λ = (331 m/s) / (20.0 Hz)

S λ = 16.6 m

37. Cicadas produce a buzzing sound that has a wavelength in air of 2.69 m. If the speed of sound in air is 346 m/s, what is the frequency of the sound produced by a cicada?

G λ = 2.69 m v = 346 m/s

U f = ?

E f = v / λ

S f = (346 m/s) / (2.69 m)

S f = 129 Hz

37. (b) What is its period?

G f = 129 Hz

U T = ?

E T = 1/f

S T = 1 / 129 Hz

S T = 7.75 x 10-3 s (0.00775 s)

38. A dolphin can typically hear sounds with frequencies up to 150 kHz. What is the speed of sound in water if a wave with this frequency has a wavelength of 1.0 cm?

G f = 150,000 Hz(150 kHz)

λ = 0.010 m(1.0 cm)

U v = ?

E v = λ·f

S v = (0.010 m)·(150,000 Hz)

S v = 1500 m/s