Shop Windows to the Universe

Learn about planets outside our solar system through Exoplanets and Alien Solar Systems by Tahir Yaqoob, Ph.D., a book in our online store book collection.
Transformers are often used in electrical circuits to change the voltage of electricity flowing through a circuit.
Click on image for full size
Image courtesy of Wikipedia (modified by Windows to the Universe staff).

Voltage Transformers in Electric Circuits

Transformers (sometimes called "voltage transformers") are devices used in electrical circuits to change the voltage of electricity flowing in the circuit. Transformers can be used either to increase the voltage (called "stepping up") or decrease the voltage ("step down").

Transformers have two coils of wire in them. The coils of wire are wound around an iron core. The wires aren't connected to each other. One wire coil has more loops than the other. When AC (alternating current) electricity flows in one wire, it makes a magnetic field around that wire. The magnetic field causes electricity to flow in the other wire. Since the wire coils have different numbers of loops, the voltage in the second wire is different from the voltage in the first wire. That's how transformers change the voltage in a circuit.

Transformers are very efficient. Under normal conditions they transmit about 99% of the power that enters them (about 1% of the power is lost as heat).

When electricity travels from a power plant to your house, it passes through transformers along the way. High voltage is good to use for sending electricity long distances through wires because less energy is lost that way. However, we need low voltage electricity in our houses because it is safer. Transformers change the voltage of electricity as it moves from a power plant to your home.

Last modified February 25, 2009 by Randy Russell.

Shop Windows to the Universe Science Store!

Our online store includes books on science education, ranging from evolution, classroom research, and the need for science and math literacy!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Direct Current (DC) & Alternating Current (AC) Electricity

There are two types of electrical currents that can flow through wires: direct current (DC) and alternating current (AC). Direct current (DC) electricity flows in the same direction all the time through...more

The Magnetic Field

The force of magnetism causes material to point along the direction the magnetic force points. Here's another picture of how this works. This picture shows where the magnetic poles of the Earth are to...more

How Space Weather Can Damage Transformers

We get electricity in our homes and schools from our electrical power system. Did you know that space weather storms can mess up the power system? When that happens, people are left without electricity....more

Space Weather Effects on Electrical Power Systems

Space weather "storms" can cause problems on Earth. They can even mess up our systems that make electricity. They can also damage the wires and other equipment used to deliver electricity to peoples' houses....more

Problems Restoring Electrical Power After a Blackout

Sometimes a whole electric power system shuts down. This can happen after a strong space weather storm. It is hard to get the whole system running again after it has been shut down all the way. The main...more

Space Weather Causes Currents in Electric Power Grids

Space weather causes electricity to flow in our atmosphere. Sometimes that electricity lights up the sky! It causes the aurora (the Southern and Northern Lights). The electric currents in the atmosphere...more

Radiation Can Damage Electronics

Radiation can damage electronic circuits. Radiation can also cause electronics to malfunction. Radiation can damage the materials used in electronics over time. That can make the electronics wear out sooner....more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF