1. Parallel Circuits Friday, April 4, 2015

2. Unit 9: Electricity Friday, 4/3 Pick up a warm-up sheet of paper from the Physics bin and use GUESS to solve the following problem: A handheld radio is powered by two 1.5 V battery. When the radio is turned on there is 40 ohms of resistance. How much resistance is in the circuit? Upcoming dates: Tuesday, 4/7 – open note quiz (DATE CHANGE) Tuesday, 4/7 – last day to turn in missing electricity assignments Thursday, 4/9 – Electricity test (grade will go on the 6SW) Friday, 4/10 – End of 5SW

3. Types of Electricity Dynamic Static Direct Current (DC) Alternating Current (AC) Series ComplexParallel Unit Overview

4. Resistors can be connected in series; that is, the current flows through them one after another. Series Circuits

5. Kirchhoff’s Rules Loop Rule: The sum of the potential differences (voltage) around any closed circuit loop is zero.

6. Resistor Circuits Series 1. total resistance is the sum of the separate resistors separate resistors R T = R 1 + R 2 + R 3 +... 2. current is the same through each resistor I T = I 1 = I 2 = I 3 =... 3. total potential difference is the sum of each V T = V 1 + V 2 + V 3 +... In other words, in a series circuit, resistance and voltage add, but current stays the same.

7. Series Circuit Example

8. Practice

9. Unit Overview Types of Electricity Dynamic Static Direct Current (DC) Alternating Current (AC) Series ComplexParallel

10. Circuit – In Series Only one path

11. Circuit – In Parallel More than one path

12. Directions Using the items in your box create a parallel circuit with three branches. Place a light bulb in each branch. When all three light bulbs have illuminated do the following: Disconnect a light bulb from one branch of the circuit. Record your observations. Disconnect two light bulbs from two branches. Record your observations.

13. What do you think? If a circuit has multiple branches will the voltage, resistance, and current behave differently? Write your thoughts in your notes.

15. Kirchhoff’s Rules Junction Rule: the sum of all currents entering the junction must equal the sum of all currents leaving the junction.

16. Parallel 1. reciprocal of the total resistance is the 1. reciprocal of the total resistance is the sum of the reciprocals of the separate sum of the reciprocals of the separate resistors resistors 1/R T = 1/R 1 + 1/R 2 +1/R 3 +... 2. total current is the sum of the current through each resistor through each resistor I T = I 1 + I 2 + I 3 +... 3. potential difference is the same across each resistor each resistor V T = V 1 = V 2 = V 3 =... In other words, in a parallel circuit, resistance adds as reciprocals, voltage stays the same, and current splits. In other words, in a parallel circuit, resistance adds as reciprocals, voltage stays the same, and current splits.

18. Practice

19. Review