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11th grade Interference and standing waves worksheet

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Interference and standing waves

Grade 11 Science Worksheet

NameDate

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

  1. A string 1.2 m long vibrates in a standing wave with 3 loops. What is the wavelength, Ari?

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

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

    • 0.8 m
    • 0.3 m
    • 0.6 m

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

    Use the picture in question 3.

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

  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
    • Constructive interference: big waves
    • No waves arrive

  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?

    • Constructive interference: louder sound
    • Destructive interference: quieter sound
    • The sound changes pitch

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

    • Destructive interference: quieter sound
    • Constructive interference: louder sound
    • The sound stops completely

  9. Noise-cancelling headphones play a sound that matches the outside noise but is shifted half a wave. What does this do, Ren?

    • It changes the noise's speed
    • It doubles the noise
    • It cancels much of the noise

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

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

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

    • A standing wave between its fixed ends
    • A wave that leaves the string
    • A single pulse that keeps going
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11th grade Interference and standing waves worksheet – printable
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About this worksheet

Interference and standing waves. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can add overlapping displacements with signs, and tell constructive (crest on crest) from destructive (crest on trough) interference.
  • I can explain that pulses pass through each other unchanged and that cancelled energy reappears at the loud spots, not destroyed.
  • I can find nodes, antinodes and wavelength on a standing wave (λ = 2L ÷ n), and string frequencies (f = nv ÷ 2L, harmonics n × f₁).
  • I can use path difference: whole wavelengths give loud spots, half wavelengths quiet ones. I can explain noise-cancelling headphones and tuning a string.

Standard: none (TX)

Words to know

interference: Two waves overlapping and adding point by point

constructive: Waves adding to make a bigger wave

destructive: Waves cancelling to make a smaller wave

node / antinode: A point that stays still / a point that swings most

harmonic: A standing wave with a whole number of loops

Common mistakes

Your child ignored a minus sign. A displacement below the middle line is negative, so it subtracts.

Your child forgot that each loop is half a wavelength. On a string, λ = 2L ÷ n, and f = nv ÷ 2L.

Your child thought destructive interference destroys energy. The energy is moved to the loud spots; it isn't lost.

Questions parents ask

What is the most common mistake with interference and standing waves?

Your child ignored a minus sign. A displacement below the middle line is negative, so it subtracts.

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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