1. Parallel Circuits Aim: How does a circuit with multiple loops affect voltage, current and resistance?

2. Parallel Circuits A circuit where components are connected “parallel” to a common power source creating MULTIPLE LOOPS for current to flow Each individual part and the entire circuit obey Ohm’s Law V1V1 R1R1 R2R2

3. Parallel Circuit Rules The voltage across each component are equal to the voltage source The total current of the circuit is equal to the sum of the currents in each branch The equivalent resistance is equal to the inverse sum of the reciprocal of each resistor

4. Equivalent Resistance When calculating the equivalent resistance in a parallel circuit, first find the COMMON DENOMINATOR first and find the sum. Finally, FLIP your answer in order to get the equivalent resistance

5. Practice Equivalences 10Ω 9Ω9Ω 9Ω9Ω 9Ω9Ω 3Ω3Ω 12Ω 24Ω Connecting more resistors in parallel, REDUCES the overall resistance

6. ?? Junction Rule The total current flowing INTO a junction of two or more wires must equal to the total current flowing OUT of the junction 10A 7A 3A

7. ?? Junction Rule 10A 6A 4A 7A 3A 5A 1A

8. Calculate the (a) equivalent resistance, (b) the total current, and (c) the current flowing through the middle resistor (a) (b) (c) R 1 = 60Ω 240V R 2 = 60Ω R 3 = 60Ω

9. Calculate the (a) battery voltage, (b) the equivalent resistance (c) the current flowing in each of the other two branches (a) (b) (c) R 1 = 10Ω ??? 4.5A R 2 = 90Ω R 3 = 9Ω

10. Summary Describe the Parallel Circuit Rules for… – Voltage – Current – Resistance Describe the Junction Rule