Hot Bulbs

You will learn about energy efficiency through calculating how much electrical energy is transformed into heat (instead of light) in a light bulb.

Watch Bill Nye: Electricity (season 1, episode 18) While you are watching, complete the questions on page 1 of the Hot Bulbs Assignment.

Then do the Hot Bulbs Lab (note: this lesson follows pages C-63 through C-66 of the Energy Text).

Complete page 2 of the Hot Bulbs Assignment (including the written parts in your journal).

Safety Notes:

• Dry the materials when you are done

• Treat the bulbs gently, as they can break

• Only use the battery provided

• Never put plugged-in electrical appliances in or near water.

Materials:

• 1 9-volt battery

• 1 flashlight bulb with socket and white plastic cover

• 1 SEPUP tray

• 1 graduated cylinder

• 1 thermometer

Procedure:

1. Use Cup E as a control group for this experiment. (Learn the difference between a "control group" and an "controlled variable" here). Decide in your group what should be placed in Cup E and what measurements should be taken for the control.

2. Using the graduated cylinder, carefully measure 12 mL of water into Cup A of the SEPUP tray. Measure the initial temperature of the water and record it in on your Hot Bulbs Assignment data sheet.

3. Insert the flashlight bulb into the white plastic cover. Be sure that the concave side of the plastic cover faces up and the bulb faces down. Screw the brass socket onto the bulb. Insert the thermometer into the plastic cover.

4. Connect the 9-volt battery to the socket, using the connectors provided. Place the lighted bulb into the water in Cup A for exactly 3 minutes.

5. After 3 minutes, remove the bulb from the cup. Measure the final temperature of the water and record it.

6. Repeat steps 2-5 two more times in Cup B and Cup C.

7. Complete calculations and questions on your Hot Bulbs Assignment data sheet.