µ IB | Standing Waves

10 quick questions

home  

 

<

10 minutes maximum! (can you do it in 5?)

 

 

 1. A standing wave is typically formed by 2 waves meeting. Which of these statements about the 2 waves is correct?

  • A. The waves must be travelling in the same direction, and have different wavelengths.
  • B. The waves must be travelling in opposite directions, and have different wavelengths.
  • C. The waves must be travelling in the same direction, and have the same wavelength.
  • D. The waves must be travelling in opposite directions, and have the same wavelength.
2-4. A travelling wave produces a changing wave displacement at all points, but a constant amplitude at all points. A standing wave, however, produces nodes and antinodes.  

2. What is the distance between consecutive nodes?

  • A. ¼λ
  • B. ½λ
  • C. λ
  • D. 2λ

3. A node is a point where...

  • A. The amplitude detected will be small, but not zero.
  • B. The amplitude detected will be zero.
  • C. The amplitude detected will be at a maximum.
  • D. The amplitude detected will rise and fall constantly.

4. An antinode is a point where...

  • A. The amplitude detected will be small, but not zero.
  • B. The amplitude detected will be zero.
  • C. The amplitude detected will be at a maximum.
  • D. The amplitude detected will rise and fall constantly.

 

5+6. A microphone is placed between two loudspeakers, producing identical in phase sound waves. A standing wave is formed between the speakers.

The wavelength of the sound is 20 cm.

 

5. The microphone is moved between P and R in the diagram. Which of these statements is correct?

  • A. The amplitude detected will be constant.
  • B. The amplitude detected will gradually increase.
  • C. The amplitude detected will gradually decrease.
  • D. The amplitude detected will rise and fall several times.

6. The microphone is moved between Q and S in the diagram. Which of these statements is correct?

  • A. The amplitude detected will be constant.
  • B. The amplitude detected will gradually increase.
  • C. The amplitude detected will gradually decrease.
  • D. The amplitude detected will rise and fall several times.

7&8. The diagram below shows a standing wave. It is produced by a sound wave inside a pipe. The pipe has not been shown.

standing wave

 

7. Which of these statements is correct?

  • A. The diagram shows the first harmonic of a pipe open at both ends.
  • B. The diagram shows the second harmonic of a pipe open at both ends.
  • C. The diagram shows the first harmonic of a pipe closed at one end.
  • D. The diagram shows the second harmonic of a pipe closed at one end.

8. How long is the pipe, in terms of the wavelength of the sound?

  • A. ¼λ
  • B. ½λ
  • C. λ
  • D. 2λ

9&10. A thin pipe of length 30cm is closed at one end. By blowing across the open end, different harmonics can be produced.

 

9. What is the wavelength of the first harmonic ?

  • A. 30 cm
  • B. 40 cm
  • C. 60 cm
  • D. 120 cm

10. What is the wavelength of the second harmonic?

  • A. 30 cm
  • B. 40 cm
  • C. 60 cm
  • D. 120 cm