#362. Heat and electrical resistance

Science, level: Middle
Posted Sat Mar 21 21:12:48 PST 1998 by D. Dauber (dauberd@sisna.com).
VVHS, Mesquite, USA
Materials Required: D cell battery, 3 different diameters of naked wire, thermometer, graph paper, clock
Activity Time: 25 min
Concepts Taught: thermal energy, resistance

Can be used in an electrical thematic unit or when studying heat and thermal energy.

The lab activity should follow a discussion of heat or electrical resistance.

Team students, 2/team

Directions: each team needs 3 different "diameters" of electrical wire - I use thin diameter wire from old, broken appliances. Wrap one of the wires around the bottom of a thermometer making sure to leave about 10-12 cm free on each end. The thermometer bulb should be completely wrapped.
Complete the circuit by connecting the ends of the wire to the + and - poles of the D cell battery. Time the rise in temperature about every 10 seconds and until the temperature stops rising. After completing this with the 3 different wires students can construct a graph of the data. Discussion questions should follow

Caution: very thin wire can generate enough heat to make touching the wire to the battery poles uncomfortable - students may need a strip of electrical tape to use as an insulator.