Waves

Wave Basics/Harmonics

1

Determine the amplitude of the wave.

1 m

2

Determine the wavelength of the wave if it is travelling at 40 m/s

120 m

3

A close-ended organ pipe emits a frequency of 150 Hz in the third harmonic. If speed of sound is 345 m/s, what is the length of the pipe?

1.725 m

4

A guitar string is 64 cm long and has a fundamental frequency of 275 Hz. Where should the string be pressed to produce a fundamental frequency of 500 Hz?

0.352 m up the string

5

An open-ended whirly tube has a length of 45 cm. Determine the wavelength produced by the third harmonic of the wave. The speed of sound is 343 m/s.

0.3 m

SHM

1

A block oscillating on a spring reaches a maximum displacement (amplitude) of 0.3 meters. If the spring constant is 100 N/m, what is the maximum potential energy stored in the spring during its oscillation?

4.5 J

2

A pendulum has a frequency of 0.60 Hz. Determine the length of the pendulum.

0.690 m

3

If a pendulum on earth had a period of 3 seconds, what would its period be on a planet where the gravity is 4 times greater?

1.5 seconds

4

Determine the maximum kinetic energy of a 4 kg mass on a spring assuming it has a period of 1.85 seconds and an amplitude of 0.67 m.

10.4 J

5

A pendulum has a frequency of 0.45 Hz and an amplitude of 2 m. Determine the speed of the pendulum after 3 seconds assuming the pendulum starts at an endpoint (may have a phase shift). Should you be in radians or degrees?

4.57 m/s

Reflection/Refraction

1

A light ray strikes a flat mirror at an angle of 30° to the surface. What is the angle of reflection relative to the normal?

60º

2

A light ray moves from air (refractive index n=1.00) into water (refractive index n=1.33) at an angle of incidence of 45°. What is the angle of refraction in the water?

33.0º

3

DOUBLE POINTS

A light ray traveling in air strikes a piece of glass (refractive index n=1.5) at an angle of incidence of 50°. Calculate both the angle of reflection and the angle of refraction.

Reflection=50º

Refraction=30.7º

4

Determine the critical angle for the surface of glass (n=1.5) and oil (n=1.2).

53.1º

5

A light ray passes from air into glass (refractive index n=1.5) and then into water (refractive index n=1.33). If the light enters the glass at an angle of 40° to the normal, what angle of refraction does it make with the normal in the water?

28.9º

Diffraction

1

What is the term for overlaying two waves on top of each other that causes interference?

Superposition

2

STEAL POINTS

Why does single-slit diffraction occur?

Light waves from the two sides of the slit interfere with each other

3

In a double-slit experiment, two slits are spaced 0.2 mm apart, and light of wavelength 500 nm is used. If the screen is placed 1 meter from the slits, what is the distance between adjacent bright fringes?

2.5 mm

4

A diffraction grating has 5000 lines per centimeter. Light of wavelength 450 nm is directed at the grating. At what angle does the first-order maximum appear?

13º

5

A single-slit diffraction experiment is conducted using a slit width of 0.5 mm and a light source of wavelength 600 nm. If the screen is placed 2 meters from the slit, what is the width of the central maximum? Hint: If the length to the first minima is 1 mm, the total width of the central maxima would be 2 mm.

4.8 mm

Doppler Effect

1

Compared to further away, how is the amplitude of a sound wave changed when you are closer.

The amplitude is greater.

2

In your own words, describe what the doppler effect is and provide an example. Be descriptive.

an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move toward (or away from) each other. The effect causes the sudden change in pitch noticeable in a passing siren, as well as the redshift seen by astronomers.

3

STEAL POINTS

A police car is driving toward a stationary observer at 30 m/s, emitting a siren at a frequency of 700 Hz. If the speed of sound in air is 343 m/s, what frequency does the observer hear?

767 Hz

4

A star’s light is blue-shifted from a wavelength of 460 nm to 445 nm. Determine the velocity of the star. The speed of light is 3 E 8 m/s.

-9.78 E 6 m/s

5

WAGER ROUND

A train is moving toward an observer at 40 m/s while the observer moves toward the train at 15 m/s. The train’s horn emits a sound at 500 Hz. What frequency does the observer hear if the speed of sound in air is 343 m/s?

591 Hz