WooHoo Way Fun Wave Stuff

Practice for the test:

1. A tuning fork vibrates at 880 Hz.  What will be the wavelength and period of the sound produced?

2. (a) Determine the wavelength of FM station 102.1 MHz.  (b) Determine the wavelength of AM station 1340 kHz.

3. A wave with period 0.078 s passes from a steel spring, where v = 2.0 m/s, to a bronze spring, where v = 3.5 m/s.  (a) Determine the frequency and wavelength in the steel spring.  (b) Determine the frequency and wavelength in the bronze spring.

4. Determine the frequency for a laser that produces light with wavelength 633 nm.

5. A microwave oven operates at frequency 2450 MHz.  Determine the wavelength of the radiation that heats the food.

6. The source of a wave affects which wave parameters?

7. The medium through which a wave travels affects which parameters?

8. What is the medium for electromagnetic radiation?

9. What is the difference between longitudinal and transverse waves?  Which of these is sound? Which of these is light?  Which of these is ultraviolet?

10. A bird on a horizontal wire bobs up and down 7.00 times in 3.00 seconds producing a wave in the wire.  A second bird is located 24.0 m away on the same wire.  The second bird is observed to start bobbing up and down 0.857 s after the first bird started bobbing.  (a) Determine the speed of the wave.  (b) Determine the frequency of the wave.  (c) Determine the wavelength of the wave. (d) Determine the period of the second bird’s oscillation. (e) Determine whether the two bobbing birds are in phase or out of phase as they bob up and down.

11. Graph the following wave on your calculator:  a sinusoidal wave with speed 35 m/s, amplitude 6.5 cm, and frequency 25 Hz.  (a) On the disturbance versus time graph determine the amount of disturbance at t = 0.050 s.  (b) On the disturbance versus distance graph determine the amount of disturbance at d = 1.0 m.

12. A certain sound wave is described by the equation y(x) = 3 sin(20x) + sin(80x),
where x = distance in meters and y = pressure change in milliPascals.
(a) Determine the wavelength of the wave.  (b) Determine the amplitude of the wave.  (c) Determine the frequency of the wave.  (d) Determine the period of the wave.

13. Two speakers produce sound waves at the same time:  wave A has wavelength 14.0 cm and amplitude 0.50 mPa, wave B has wavelength 14.0 cm and amplitude 0.30 mPa.  Determine the wavelength and amplitude of the superposition of these two waves and state the type of interference for two cases:  (a) the two waves are exactly in phase, (b) the two waves are exactly out of phase.

14. A drainage pipe is open at both ends and is 4.00 m long.  At certain times the wind blows just right and the pipe is heard to whistle.  Determine the most probable frequencies of the pipe’s whistling sound.

15. A kid has a straw in his soda.  He blows across the end of the straw and produces a high-pitched sound.  What would be the possible frequencies of sound produced if the open end of the straw is 7.00 cm above the level of the soda in the glass?

16. A certain bass guitar has a string that is 80.0 cm long that has a fundamental frequency of 55.0 Hz (the A string).  (a) Determine the frequencies and wavelengths of the 2^nd and 3^rd harmonics for this string.  (b) Determine the speed of waves traveling through this guitar string.  (c) If another string on the same guitar is to have a fundamental frequency of 73.4 Hz, what must be the speed of waves in that string to produce this result?

17. Mr. M uses a microwave generator for classroom demonstrations.  The generator produces microwaves at frequency of 10.525 GHz.  In one demo the waves are reflected back toward the wave generator by a metal plate.  As a microwave detector is moved through the region between the generator and the metal plate it is found that there are alternating regions of strong microwaves and no microwaves.  (a) Describe what happens between the generator and the metal plate that produces the alternating pattern.  (b) Determine the distance between one strong microwave reading and the next strong microwave reading.

18. Laser light of wavelength 520.0 nm passes through two slits that are separated by 3.5 × 10^-5 m.  The light falls upon a screen that is 3.00 m away from the slits.  (a) Determine the distance from the principle image to the 2^nd order image.  (b) Determine the distance between the dark lines that are observed on either side of the principle image.

19. Light of an unknown wavelength is passed through a diffraction grating with 460 lines/mm.  The angle between the principle image and the 1^st order image is 20.0°.  (a) Determine the wavelength of the light.  (b) Find the angle between the 1^st and 2^nd order images. 

20. In a classroom demonstration two speakers act in phase to produce sound with a frequency of 245 Hz.  Determine the type of interference that occurs for each of the following students in the class:  (a) Johnny is 2.00 m away from one speaker and 2.70 m away from the other. 
(b) Suzy is 0.50 m away from one speaker and 3.30 m away from the other.  (c) For each student give the path difference in multiples of the wavelength.

1. 0.390 m, 1.14 ms

2. a. 2.94 m
b. 224 m

3. steel: 13 Hz, 0.16 m
bronze:  13 Hz, 0.27 m

4. 4.74 ´ 10¹⁴ Hz

5. 0.122 m

6.

7.

8.

9.

10. a. 28.0 m/s
b. 2.33 Hz
c. 12.0 m
d. 0.429 s
e.

11. a. t = 0.050 s, y = 6.5 cm
b. x = 1.00 m, y = -6.34 cm

12. a. 18 m
b. 3.81 mPa
c. 19.1 Hz
d. 0.0525 s

13. a. 14.0 cm, 0.80 mPa
b. 14.0 cm, 0.20 mPa

14. 42.9 Hz, 85.8 Hz, 129 Hz, . . .

15. 1225 Hz, 3675 Hz, 6125 Hz, . . .

16. a. 110 Hz, 0.800 m; 165 Hz, 0.533 m
b. 88.0 m/s
c. 117 m/s

17. a.
b. 1.425 cm

18. a. 8.92 cm
b. 4.46 cm

19. a. 744 nm
b. 23.2°

20. a. destructive interference
b. constructive interference
c. Johnny: ½ l; Suzy: 2 l