Science 9 · Unit 6: Sound and space · Cambridge Lower Secondary Science Stage 9

Questions

1. 1. How do noise-cancelling headphones work?

   • They make the noise louder.
   • They make a sound wave that cancels the incoming noise.
   • They change the noise to a higher pitch.
   • They block all air from the ears.
   Check

2. 2. Can sound waves interfere with water waves?

   • No, interference only happens between waves of the same type.
   • Yes, any waves can interfere.
   Check

3. 3. What happens when a sound is reinforced?

   • It becomes louder.
   • It becomes higher pitched.
   • It becomes lower pitched.
   • It becomes quieter.
   Check

4. 4. Two identical waves meet exactly in step. What does the resulting wave look like?

   • a flat line
   • double the frequency, with the same amplitude
   • the same frequency, with double the amplitude
   • half the amplitude
   Check

5. 5. Zara and Sofia play the same note at the same time. Why does it sound louder than when they play separately?

   • The sound waves reinforce.
   • The sound waves cancel.
   • The sound waves make a higher pitch.
   • The sound waves make a lower pitch.
   Check

6. 6. Two identical notes reinforce. What happens to the pitch Arun hears?

   • It goes higher.
   • It goes lower.
   • It disappears.
   • It stays the same.
   Check

7. 7. Another sound of the same pitch cancels the sound from a loudspeaker. What does Arun hear?

   • a higher pitched sound
   • a much louder sound
   • silence, or a much quieter sound
   • a lower pitched sound
   Check

8. 8. Which wave would reinforce wave S?

   • one with the same frequency and amplitude, exactly out of step
   • one with the same frequency and amplitude, exactly in step
   • one with double the frequency
   • a flat line with no vibration
   Check

9. 9. Which wave would cancel wave S?

   • one with the same frequency and amplitude, exactly out of step
   • one with the same frequency and amplitude, exactly in step
   • one with double the frequency
   • one with half the amplitude, in step
   Check

10. 10. Waves A and B reinforce to give C, with double the amplitude of A. How do the amplitudes of A and B compare?

    • B is half A.
    • B is zero.
    • They are the same.
    • B is double A.
    Check

11. 11. Waves A and B, with the same pitch, reinforce to give wave C with double the amplitude. How do the frequencies of A and B compare?

    • B is zero.
    • B is half A.
    • B is double A.
    • They are the same.
    Check

12. 12. How does the frequency of wave C compare with the frequency of wave A?

    • It is zero.
    • It is the same.
    • It is half.
    • It is double.
    Check

13. 13. Waves D and E cancel completely. How do their amplitudes and frequencies compare?

    • The frequencies differ but the amplitudes are the same.
    • The amplitudes differ but the frequencies are the same.
    • Both are the same.
    • Both are different.
    Check

14. 14. Particle P vibrates 1 mm each way at 2500 Hz. Another identical wave reinforces it. What is P's frequency now?

    • 2500 Hz
    • 1250 Hz
    • 5000 Hz
    • 0 Hz
    Check

15. 15. What is P's amplitude when the two waves reinforce?

    • 2 mm
    • 1 mm
    • 0 mm
    • 0.5 mm
    Check

16. 16. Particle P vibrates 1 mm each way at 2500 Hz. Wave Q cancels it completely. What are Q's frequency and amplitude?

    • 2500 Hz and 2 mm
    • 2500 Hz and 1 mm
    • 1250 Hz and 0.5 mm
    • 5000 Hz and 1 mm
    Check