How do we know?
↻ One of the pages with a moving picture
Michael Faraday found out how to make a current with a magnet.
- Electricity is electrons moving between atoms. Atoms are the tiny building blocks of everything.
- At a dam, flowing water spins a turbine. The turbine turns a generator.
- Inside, a magnet moves near a coil of wire. That pushes electrons along the wire. Zap: a current!
- Power lines carry it to your home. Flip a switch on, and it completes the circuit.
In 1831, scientist Michael Faraday found that moving a magnet inside a coil of wire makes a current. Most of the world’s electricity comes from generators based on his discovery.
Hoover Dam on the Nevada–Arizona border has 17 main turbines: nine on the Arizona side and eight on the Nevada side.
About 6% of U.S. electricity comes from water power, like at Hoover Dam.
Wow number
4.2 billion Kilowatt-hours of electricity Hoover Dam made in an average year from 1947 to 2008.
Myth or fact?
Power plants make electricity out of nothing. Myth. Generators change the energy of motion into electricity.
Electricity needs a complete path to flow. Fact. That path is called a circuit. A switch opens or closes it.
Think about it
About 6% of U.S. electricity comes from water power, like at Hoover Dam. Where do you think your electricity comes from?
Where in the world?
Hoover Dam, Nevada–Arizona border, USA which has 17 main turbines: nine on the Arizona side and eight on the Nevada side — 36.016° N, 114.7377° W.
Where these facts come from
Every number on page 94, and who measured it
This page tells us how much U.S. electricity comes from water power.
Electricity in the U.S. — The U.S. Energy Information Administration, which keeps facts about energy
eia.gov/kids/energy-sources/electricity/electricity-in-the-us.php
We checked it on 31 October 2026
This page tells us how generators, magnets and wires make electricity.
Science of electricity — The U.S. Energy Information Administration, which keeps facts about energy
eia.gov/kids/energy-sources/electricity/science-of-electricity.php
We checked it on 31 October 2026
This page tells us about Hoover Dam's turbines and how much power they make.
The U.S. Bureau of Reclamation, which runs Hoover Dam
usbr.gov/lc/hooverdam/faqs/powerfaq.html
We checked it on 31 October 2026
Has this changed?
How electricity gets to your house is not going to change.
Where the electricity comes from does change over time, and it differs from place to place.
Words from this page
- electron
- A tiny bit of an atom that moves along a wire to make electricity.
- generator
- A machine that turns movement into electricity.
- circuit
- A complete path that electricity can flow around.
Try it!
Find out why a flashlight needs a complete circuit.
1. With a grown-up, take the batteries out of a flashlight. 2. Click it on. What happens? 3. Put the batteries back the right way. Click it on again.
What happens: with no batteries, the path is broken and nothing lights. Put them back, and the circuit is complete!
Go further