Lesson 5 of 6 · Magnetism
Lesson⭐ 30 XP⚡ Spark LabTransformers and the National Grid
Magnetism.
🎯 Your mission
Master the concept. Use it tomorrow.
⚡ The twist
Energy never disappears — it just hides somewhere else.
Mind = Blown
⚡ Static electricity is the same physics as lightning, just smaller.
Make a hypothesis first
Before you start: which will move faster, and why?
What You'll Learn
A transformer changes the potential difference of an alternating supply using two coils on a shared iron core. Stepping voltage up reduces current for the same power, and because power loss in cables is I²R, high-voltage transmission wastes far less energy.
Key Words
Tap a word to see its definition.
Steps
Read the explanation above and note the two key terms before you start.
Calculate the current needed to deliver 400 kW at 400 V and at 400 kV. Then use P = I²R with a cable resistance of 5 Ω to find the power wasted in each case and express the saving as a percentage.
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 2Power loss in transmission cables is reduced mainly by:
Where you see this in real life
You use this every time you flip a light switch, ride a bike, or kick a ball.
Stretch Challenge
Try this in real life this week.
Time how long a small ball rolls down something, then change the slope and try again.
For the dinner table
“Show me something at home that uses this kind of energy.”
Next Smart Experiment
We'll pick an experiment that matches exactly how you're thinking right now.
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Transformers and the National Grid
Master the concept. Use it tomorrow.
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