Mon Prof Augmenté
Power in a circuit
Age 14 · Physics
Electrical power is voltage multiplied by current. A device that uses more power transforms electrical energy faster, so it uses more energy over time.
This picture is part of the full library
Every lesson is open to everyone for 7 days after it is published. This one came out on October 13, 2026: its text stays readable here, and its picture opens with a subscription.
The app is free. A subscription opens every lesson, in every school year.
In the picture
- The battery pack: the source that supplies voltage to the circuit
- The meter in line with the bulb: it shows the current through the circuit
- The meter connected across the bulb: it shows the voltage across the bulb
- The small glowing bulb: a device using electrical power, glowing less brightly
- The larger lamp on the thicker cable: a device using more electrical power, glowing more brightly
Examples
- A phone charger might use about 10 W, while a kettle might use about 2000 W.
- A 10 W LED bulb left on for 5 hours uses 50 Wh of electrical energy.
Key takeaways
- Power in watts equals voltage in volts multiplied by current in amperes.
- Energy used equals power multiplied by the time the device is on.
Quiz: Power in a circuit (Age 14)
-
What is the formula for electrical power in a circuit?
-
How do you calculate the energy a device uses?
-
If a device uses more electrical power, what happens to how fast it transforms electrical energy?
The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.
Free app, optional subscription
App Store Google Play
Carry on in the app
At least one new illustrated lesson every weekday for your child’s year, with its quiz and a reminder at 6:15 pm.
Your child’s teacher does not use My Enhanced Teacher yet?
Tell them about it
