Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Energy and Dimmer Switches
Name: Jack
Status: Other
Age: Old
Location: N/A
Country: N/A
Date: April 2002

Does a dimmer switch on a light actually save energy?

A dimmer switch allows you to control the amount of current flow to the light bulb. To answer your question you can save energy if you did not want to have your lights ON "full blast". However, you do not get something for nothing. The energy you saved is as a result of the decreased intensity of your lights.


Assuming that the dimmer is a "step-down" A. C. transformer, it should reduce the power used. If it is a variable resistor then it would not reduce the power used. I think most dimmers are the transformer type since the resistor would generate a lot of heat due to Ohms Law heating E = i x V.

Vince Calder

Click here to return to the Engineering Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory