Hooked on Science: Toilet-paper tube light bulb

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 batteries together in a series.
• Step 2: Use the tape to secure the alligator clips to the sides of the toilet-paper roll.
• Step 3: Place a 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, clips and pencil lead.
• Step 5: Close the circuit by touching the ends of the alligator clips to the ends of the roll of batteries. Make observations to provide evidence energy can be transferred from place to place by electric currents.

Explanation

The electrons from the battery flow through the alligator clips and pencil lead, creating a closed circuit. The pencil lead, or filament, becomes so hot, it glows, weakens and eventually breaks.