Lesson 8 of 8 · Waves
Experiment⭐ 30 XPThe Doppler Effect
The Doppler Effect.
🎯 Your mission
Set it up. Test it. Be amazed.
⚡ The twist
Nature loves to surprise the careful watcher.
Mind = Blown
🔬 The more you look, the more nature shows you.
Make a hypothesis first
Before you start: write down what you think will happen, and why.
What You'll Learn
When a source moves towards you, each wave is emitted a little closer than the last, so the wavelength you receive is shortened and the pitch rises. Moving away, it lengthens and the pitch falls. Astronomers use the same effect as redshift to measure how galaxies move.
Key Words
Tap a word to see its definition.
Materials Needed
- phone with spectrum analyser app
- safe viewpoint well back from a road
Safety First
- Stay well behind a barrier or fence — never stand at the roadside.
- Go with an adult.
Steps
Read the explanation above and note the two key terms before you start.
Stand safely back from a road and record a passing vehicle's siren or engine on your phone. Analyse the recording with a spectrum app and measure the frequency before and after it passes.
Record what actually happened, including anything that did not match what you expected.
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Check Your Understanding
Question 1
1 of 2A siren's pitch as an ambulance passes and moves away:
Where you see this in real life
This shows up in your everyday life more than you'd think.
Stretch Challenge
Try this in real life this week.
Try one experiment in real life this week — even a tiny one.
For the dinner table
“What's the most surprising thing you learned today?”
Next Smart Experiment
We'll pick an experiment that matches exactly how you're thinking right now.
Share this experiment
Send it to a parent who's looking for a 10-minute kitchen science win.
Ready?
The Doppler Effect
Set it up. Test it. Be amazed.
Full screen — no distractions
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