1. Investigation 13.1: Short Circuits
Purpose: To learn how a short circuit changes how current travels in a circuit.
Name: ___________________________________
What is a Short Circuit?
A short circuit is an easy (but dangerous) shortcut
that current can travel through in a circuit.
A. Procedure
Remember: current is measured across the ___________________
Circuit 1:
Three bulbs,
NO short circuit
Build the circuit from yesterday (above) with three bulbs, two batteries, and one switch.
Measure the current. Record current and bulb activity in Table 1.
Now rebuild the circuit from yesterday (below) with only one bulb.
Measure the current. Record current and bulb activity in Table 1.
Now, build a circuit (below) with three bulbs and a short circuit.
Measure the resistance of a light bulb: Record the resistance in Table 2.
Measure the resistance of a wire. Record the resistance in Table 2.
Circuit 2:
One bulb,
NO short circuit
Circuit 3:
Three bulbs,
short circuit.

2. Table 1: Current Table 2: Resistance
B. Data
Table 1: Current
Circuit 1: Three bulbs, no short circuit
Current (A)
Circuit 2: One bulb, no short circuit
Circuit 3: Three bulbs, short circuit
Did bulbs light up?
Brightness?
Table 2: Resistance
Resistance of a light bulb (Ω)
Resistance of a wire (Ω)
C. Analysis
Please answer in complete sentences when appropriate.
Current of three bulbs, NO short circuit (Circuit 1): ________________________
Current of three bulbs, WITH a short circuit (Circuit 3): _____________________
Which circuit had a greater current - three bulbs with NO short circuit or three bulbs WITH a short circuit?________________________________________________________________________________ ________________________________________________________________________________
Current of one bulb, NO short circuit (Circuit 2): ________________________
Current of three bulbs, WITH short circuit (Circuit 3): _____________________
How did the current from Circuit 2 and 3 compare? ________________________________________________________________________________________________________________________________________________________________

3. 7. What is the path the current travels in Circuit 3
7. What is the path the current travels in Circuit 3? (Hint: Look at which light bulbs lit up.) ___________________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________
8. WHY do you think the current travels in that path? Provide evidence from the lab to support your answer. (Hint: look at your resistance data from Table 2.) ________________________________________________________________________________________________________________________________________________________________________ ____________________________________________________________________________________