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Benjamin Franklin Was Lucky.
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This experiment appears in the section "How Electricity Can Hurt You."
Materials:
Students will need the circuits they made for the "Complete a Circuit" experiment, modified as shown in the illustration (strip a 2.5-cm section of insulation off the middle of each wire). Students will also need a 15-cm piece of thicker wire with 2.5 cm of insulation removed at each end.
Safety First:
- Students should be supervised by an adult while doing this experiment.
- A teacher or another adult should be responsible for stripping insulation from wires.
- Remind students that they are able to work with these batteries and wires because the voltage is minimal (1.5 V per D-cell battery). They should never experiment with the electricity that comes from a power point. It's much more powerful than the electricity made by small batteries and could seriously injure or even kill someone.
Objective:
Through creating a short circuit, students will understand that Benjamin Franklin got shocked because he touched two parts of a circuit at the same time.
Getting It Across:
- Have students read the information and follow the steps on the page.
- Be sure students understand that they should immediately disconnect the thick wire and the battery after they observe what happens. The wires will get hot. This is a clue to why Franklin got shocked.
Questions and Answers:
- Students' predictions and results will vary.
- Why is this called a "short circuit"? (Because the electricity travels a shorter route than the intended circuit. Electricity is not able to complete its intended path because the circuit is grounded somewhere.)
- Why did Benjamin Franklin get shocked? (His arms functioned like the thick wire in the experiment. Electricity traveled through his body instead of through the circuit.)
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