Year 9 Science · Unit 4 · Lesson 4
Foundation Worksheet
Learning Goals
Match each formula to what it calculates
Draw a line connecting each formula on the left to the correct quantity on the right. Or write the matching letter next to each formula.
| Formula | Your answer | What it calculates |
|---|---|---|
| v = f × λ | A. Frequency (Hz) — how many waves per second | |
| f = v ÷ λ | B. Wavelength (m) — the length of one wave | |
| λ = v ÷ f | C. Wave speed (m/s) — how fast the wave travels |
Worked example table — fill in the missing values
Use the wave equation to complete the table. Show your working in the space below the table.
| Speed (v) | Frequency (f) | Wavelength (λ) | Formula used |
|---|---|---|---|
| 340 m/s | 170 Hz | λ = v ÷ f | |
| 3 × 10⁸ m/s | 1 m | f = v ÷ λ | |
| 500 Hz | 0.5 m | v = f × λ | |
| 1500 m/s | 250 Hz | λ = v ÷ f |
Working space:
True or False? Fix the false ones
Circle T or F for each statement. If the statement is false, rewrite it correctly on the line below.
In the formula v = fλ, the letter v stands for volume.
Correct it:
If wave speed stays constant and frequency increases, the wavelength must decrease.
Correct it:
The speed of light in a vacuum is approximately 3 × 10⁸ m/s.
Correct it:
Sound travels faster than light, which is why you hear thunder before seeing lightning.
Correct it:
1. A guitar string vibrates at 440 Hz. The speed of sound in air is 343 m/s. Calculate the wavelength of the sound wave produced. Show your working.
2. Explain why a high-pitched sound and a low-pitched sound can travel at the same speed in air, even though they have different frequencies. Use the wave equation in your answer.
Wrap Up
In one sentence, what was the main idea of this lesson?