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Worksheet9th GradeLevel 2 · Standard

Free 9th Grade Sound Waves: Frequency, Wavelength and the Wave Equation Worksheet

Students describe sound as a longitudinal wave of compressions and rarefactions and define amplitude, wavelength, frequency and period, linking frequency to pitch and amplitude to loudness. They use the wave equation v = fλ to calculate speed, frequency and wavelength, calculate distances from echoes, sonar and thunder, and explain why sound travels at different speeds in solids, liquids and gases but not at all in a vacuum.

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Grade
9th Grade
Subject
Science
Topic
Energy, Light, Sound & Electricity
Difficulty
Level 2 · Standard
Estimated time
45 minutes
Curriculum
Texas grade levels (TEKS)
Questions
15
Answers
Included, with working
Format
PDF (A4), print or complete online

Students will practice

  • describing sound as a longitudinal wave
  • defining amplitude, wavelength, frequency and period
  • linking frequency to pitch and amplitude to loudness
  • using the wave equation v = fλ
  • calculating distances from echoes and sonar

Curriculum: Texas grade levels (TEKS). We show specific outcome codes only where they have been verified against the official curriculum document.

What's next?

Completed: Sound Waves: Frequency, Wavelength and the Wave Equation

  1. 1Electricity: Current, Voltage, Resistance and Ohm's Law
  2. 2Light: Reflection, Refraction and the Electromagnetic Spectrum
Harder: Level 3 · Challenge →

How to use this worksheet

  1. Print the PDF or complete it on screen. Write the student's name and date at the top.
  2. Read the instructions for each part together before starting. Encourage working to be shown.
  3. Mark with the answer sheet. Use the model answers and success criteria as a guide rather than a single right answer.
  4. Record the score, celebrate what went well, then follow the "What's next" suggestion.

Common questions

Who is this worksheet for?

9th Grade students (typically ages 14–15) working on energy, light, sound & electricity. It is pitched at level 2 · standard; a harder version is linked above.

Are the answers included?

Yes. The PDF includes a full answer sheet with model answers and success criteria where there is more than one good answer. You can also view the answers online.

How long does it take?

About 45 minutes for 15 questions. Short, regular sessions work best: two or three a week beats one long one.

Do I need to sign up to download?

No. Click Download Free PDF and it opens immediately. It is free for personal, classroom and homeschool use.

What should we do next?

Try Electricity: Current, Voltage, Resistance and Ohm's Law.

Preview

Success TutoringWorksheets9th Grade · Science · Energy, Light, Sound & Electricity

Sound Waves: Frequency, Wavelength and the Wave Equation

Name

Date

Score /

For echo questions, always halve the total distance: the sound goes there and back.

Part A: What is a sound wave?

Sound is made by vibrating objects. The vibrations push and pull on the air particles, producing compressions (particles squashed together) and rarefactions (particles spread apart) that travel outwards. Because the particles vibrate along the direction the wave travels, sound is a longitudinal wave.

Frequency (in hertz, Hz) decides pitch: higher frequency, higher pitch. Amplitude decides loudness. Humans can hear roughly 20 Hz to 20,000 Hz. Period = 1 ÷ frequency.

1.Match each wave term to its meaning.
  • Amplitude
  • Wavelength (λ)
  • Frequency (f)
  • Period (T)
  • The number of waves passing a point each second, in hertz
  • The time for one complete wave to pass
  • The maximum disturbance from the rest position
  • The distance from one compression to the next
2.A guitar string is plucked harder, but at the same place. What changes?
  1. AThe pitch gets higher
  2. BThe sound gets louder
  3. CThe sound travels faster
  4. DThe wavelength gets shorter
3.Sound waves are transverse waves, like waves on a rope. ☐ True   ☐ False
4.Astronauts on a spacewalk cannot talk to each other directly and must use radios. Explain why. (answer space)
5.A sound has a frequency of 50 Hz. What is its period?

Part B: The wave equation

Wave speed = frequency × wavelength, or v = fλ, with v in m/s, f in Hz and λ in m. Rearranged: f = v ÷ λ and λ = v ÷ f.

Use 340 m/s for the speed of sound in air.

6.A tuning fork produces a note of 680 Hz in air. What is its wavelength?
7.A sound in air has a wavelength of 1.7 m. What is its frequency?
8.Calculate the wavelengths of the lowest (20 Hz) and highest (20,000 Hz) sounds humans can hear.
9.If the frequency of a sound in air is doubled, what happens to its wavelength? Explain using v = fλ. (answer space)

Part C: Echoes and sonar

An echo is a reflected sound. When using an echo to measure distance, remember the sound travels to the object and back, so divide the total distance by 2.

10.A student claps in front of a large cliff and hears the echo 2.0 s later. How far away is the cliff?
11.A ship's sonar sends a pulse to the sea floor and receives the echo 0.8 s later. Sound travels at 1500 m/s in sea water. How deep is the water?
12.You see a flash of lightning and hear the thunder 3 s later. Roughly how far away was the lightning?
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Preview — the PDF contains the full resource and answer sheet.

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About this resource

Created by
Success Tutoring Science Team
Last reviewed
1 October 2026
How it was made
Written by our team

Free to print and share for personal, classroom and homeschool use. Please don't resell. Spotted an error? Let us know.