Plan for Today (AP Physics I)

1. Plan for Today (AP Physics I) • Inquiry questions on circuits • Lecture on Series and Parallel Circuits

2. Parallel and Series Circuits Parallel Series

3. Instructions • Create a series and parallel circuit with three capacitors and charge them with 6 V • Measure the voltage across each capacitor • Discharge the circuit with a light bulb noting the length of time. • Sketch your set up and label the voltages • Describe the differences between the two circuits (include V and q)

4. Series and Parallel Circuits

5. Series Circuit • Single path around • Steps • 1. An electron is pushed out of the negative end of the battery and deposited on the 1st plate • This pushes an electron off the opposite plate on to the next plate • This repeats with the next capacitor down the line until one electron reaches the battery • The whole process repeats until the energy of the battery (voltage) is completely used

6. In a series circuit • What is the same? • q for each the same • What is different? • voltage

7. Energy of the battery is spread out over all the capacitors

8. Series Circuits • We would like to collapse capacitors down to one equivalent capacitor • It would help us solve for values

9. Ceq is what the 3 capacitors in series act like • So what is the same? • q on each • qeq = q1 = q2 = q3

10. VB = V1 + V2 + V3 • Because voltage is distributed across • C = q/V • So V = q/C – can sub in

11. But all the q’s are the same • Series Circuit equation

12. Example • Solve the following circuit. Find q1, q2, q3 and v1, v2, and v3.

17. Parallel Circuit • Has multiple paths

18. Parallel Circuits Diagram Flow of electrons 1. Look at C1 first. An electron is pulled off and deposited until all the energy of the battery is used 2. This repeats with the 2nd and 3rd capacitors. What is the same for each capacitor? Voltage

19. Parallel Circuits

20. Parallel Circuits - Calculations

21. Example Problem – Parallel Circuits • Analyze the following circuit and find V1, V2, and V3 and q1, q2, and q3.

22. Example Problem – Parallel Circuits • Analyze the following circuit and find V1, V2, and V3 and q1, q2, and q3.