Interference and standing waves

Answer Key - Grade 11 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Waves travel at 120 m/s on a string 0.6 m long. What frequency makes a standing wave with 1 loop, Ari?

   100 Hz
2. 2.

   Waves travel at 240 m/s on a string 0.8 m long. What frequency makes a standing wave with 3 loops, Bo?

   450 Hz
3. 3.

   Waves travel at 90 m/s on a string 0.5 m long. What frequency makes a standing wave with 2 loops, Esme?

   180 Hz

4. Read this first

   Standing waves on one string (example data)

   Loops	Frequency (Hz)
   1	100
   2	200
   3	300
   4	?

5. 4.

   Using the table, what frequency gives 4 loops, Jun?

   • 500 Hz
   • 1600 Hz
   • 400 Hz
6. 5.

   Using the table, the string is 0.5 m long. How fast do waves travel on it, Kira?

   • 50 m/s
   • 100 m/s
   • 200 m/s
7. 6.

   Using the table, why can't this string make a standing wave at 250 Hz, Luz?

   • It isn't a whole-number multiple of 100 Hz
   • 250 Hz is too high for any string
   • Standing waves need odd numbers of loops
8. 7.

   Milo says destructive interference destroys energy. Agree or disagree?

   • Agree: the quiet spots soak it up for good
   • Disagree: the energy moves to the loud spots
   • Agree: cancelled waves lose their energy
9. 8.

   Noah says two pulses that cancel while overlapping are gone for good. Agree or disagree?

   • Agree: cancelling uses them up
   • Agree: they join into one flat rope
   • Disagree: each carries on after they pass
10. 9.

    Pia says the nodes on a standing wave are points where two waves always cancel. Agree or disagree?

    • Agree: the two waves meet out of step there
    • Disagree: nodes are where the string moves most
    • Disagree: nodes move along the string
11. 10.

    A string's lowest note is 200 Hz. What is it if the string is held at half its length, Ren?

    • 400 Hz
    • 200 Hz
    • 100 Hz