Interference and standing waves

Answer Key - Grade 11 Science Worksheet

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

1. 1.

   A string 1.8 m long vibrates in a standing wave with 4 loops. What is the wavelength, Bo?

   0.9 m
2. 2.

   A string 2.4 m long vibrates in a standing wave with 3 loops. What is the wavelength, Esme?

   1.6 m
4. 3.

   In the wave diagram, what is the wavelength, Jun?

   • 0.4 m
   • 0.8 m
   • 1.2 m
5. 4.

   In the wave diagram, the same string is made to vibrate with 4 loops instead. What is the new wavelength, Kira?

   Use the picture in question 3.

   • 0.8 m
   • 0.6 m
   • 0.3 m
6. 5.

   In the wave diagram, how is the standing wave made, Luz?

   Use the picture in question 3.

   • Waves reflected from the ends overlap the incoming ones
   • One wave travels along and stops
   • The string stops moving in places on its own
7. 6.

   Two dippers make ripples in step in a water tank. A point is the same distance from both. What happens there, Milo?

   • Destructive interference: calm water
   • No waves arrive
   • Constructive interference: big waves
8. 7.

   Two speakers play the same note in step, with a wavelength of 0.8 m. A spot is 0.4 m farther from one speaker. What happens there, Noah?

   • The sound changes pitch
   • Constructive interference: louder sound
   • Destructive interference: quieter sound
9. 8.

   The same speakers, wavelength 0.8 m: a spot is 0.8 m farther from one speaker. What happens there, Pia?

   • Constructive interference: louder sound
   • Destructive interference: quieter sound
   • The sound stops completely
10. 9.

    Two sets of ripples cross in a water tank. Why are there lines of calm water, Tala?

    • The water there is shallower
    • Crests meet troughs there and cancel
    • The ripples stop there
11. 10.

    What kind of wave makes a plucked guitar string sound a steady note, Zee?

    • A single pulse that keeps going
    • A wave that leaves the string
    • A standing wave between its fixed ends