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.

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? ________________________________________________________________________________________________________________________________________________________________

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.) ________________________________________________________________________________________________________________________________________________________________________ ____________________________________________________________________________________