Lesson 6 of 8 · Waves
Experiment⭐ 30 XPTotal Internal Reflection and Optical Fibres
Total Internal Reflection and Optical Fibres.
🎯 Your mission
Run the experiment. Find out what really happens.
⚡ 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 light travels from a denser to a less dense medium beyond the critical angle, it reflects entirely back inside. Optical fibres exploit this to carry light for kilometres with almost no loss, which is what carries most internet traffic.
Key Words
Tap a word to see its definition.
Materials Needed
- laser pointer
- semicircular acrylic block
- protractor
- bottle with a hole
- dark room
Safety First
- Never look into a laser beam or aim it at anyone — even low-power pointers damage the retina.
- Keep the laser well away from the water.
Steps
Read the explanation above and note the two key terms before you start.
Shine a laser pointer into a curved stream of water falling from a bottle in a darkened room. Observe the light following the curve, then measure the critical angle of a semicircular acrylic block with a protractor.
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 2Total internal reflection occurs when the angle of incidence is:
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?”
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Total Internal Reflection and Optical Fibres
Run the experiment. Find out what really happens.
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