Hooked on Science: You can find out how a fan cools

A fan feels good on a hot summer day, but does it really create a cool breeze? You can put your fan to the test. All you need are a few materials from around the house.

Materials

* Two thermometers

* Portable fan

Instructions

STEP 1: Place one of the thermometers in front of the fan.

STEP 2: Place the other thermometer in a location that is not close to the fan.

STEP 3: Record the temperature of both thermometers. Turn on the fan and in about five minutes record the temperature of both thermometers. Did the fan lower the temperature of the air?

Explanation

The fan does not lower the temperature of the air. It feels cooler because the breeze from the fan increases the evaporation of sweat from your skin. Evaporation is a cooling process.

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website www.hookedonscience.org for webcasts and experiments that might get you hooked on science. Send him your science questions at jlindseyhookedonscience.com. More science experiments can be found at www.semissourian.com.