Hooked on Science: Build a lightbulb

Thursday, January 17, 2013

Create a light bulb by using a few ingredients from around the house.

Materials

* Electrical tape

* 8 "D" batteries

* 0.7 mm pencil lead

* Mason jar

* 2 wires with alligator clips

* Toilet paper roll

Instructions

STEP 1: Use the electrical tape to secure all the "D" batteries together in a series.

STEP 2: Use the electrical tape to secure the alligator clips to the sides of the toilet paper roll.

STEP 3: Place a 0.7 mm piece of pencil lead between the alligator clips at the top of the toilet paper roll.

STEP 4: Place the Mason jar over the toilet paper roll, alligator clips and 0.7 mm piece of pencil lead.

STEP 5: Close the circuit by touching the ends of the alligator clips to the ends of the roll of batteries.

Explanation

The electrons from the battery flow through the alligator clips and pencil lead, which is actually graphite, creating a closed circuit. The graphite, or filament, becomes so hot it glows and fills the Mason jar with smoke.

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website www.hookedonscience.org for webcasts and experiments.

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