1. Warm-Up: April 13/14, 2016
A 9.0 V battery is connect to a 8250 Ω resistor.
How much current flows through the resistor?
What is the power consumed by the resistor?
How much power is produced by the battery?

2. Homework Questions?

3. Series and Parallel Circuits
Chapter 23
Series and Parallel Circuits

4. Series Circuit
A series circuit has all current flowing through every device.
Only one path for current to follow
Does not include connected voltmeters
The equivalent resistance for the entire circuit is the sum of all resistances

5. Series Circuit Diagrams

6. You-Try #1 Find the equivalent resistance.
Find the current passing through each resistor.
Find the electric potential difference across each resistor.

7. Parallel Circuits
Parallel circuits have several paths for the current to follow
There is different amounts of current flowing through different portions of the circuit
The equivalent resistance is given by

8. Parallel Circuit Diagrams

9. You-Try #2 Find the equivalent resistance.
Find the current passing through each resistor.
Find the electric potential difference across each resistor.

10. Comparison of Series & Parallel
A series circuit has all current flowing through every device.
Parallel circuits have several paths for the current to follow

11. Series Circuits Parallel Circuits
Constant current through every element
Different ΔV across each element
Adding more elements increases equivalent resistance
Different currents through each path
Constant ΔV across each path
Adding more elements decreases equivalent resistance

12. Combined Series-Parallel Circuits
Most real circuits have some elements in series and some in parallel

14. Kirchhoff’s Rules
Kirchhoff’s first rule – the junction rule: The sum of all currents entering a junction must equal the sum of all currents leaving the junction.
Kirchhoff’s second rule – the loop rule: The algebraic sum of changes in potential around any closed circuit path (loop) must be zero.

15. You-Try #3
Find the current through each resistor

16. Short Circuit
A short circuit is when a circuit has very low resistance, causing very high current.
More current  more heat
If not prevented, this could cause a fire
The term short circuit is commonly misused to describe any electrical problem

17. Warm-Up:
Calculate the equivalent resistance of each of the following circuits.

18. Ammeters and Voltmeters
Ammeters measure current
Positioned in series with the measured current
Voltmeters measure electric potential difference (voltage)
Positioned in parallel to the measured V
Multimeters are devices with the capability of measuring current, electrical potential difference, resistance, and sometimes other variables

19. Home Electricity – Fuse Boxes
Too much current is bad!
Old buildings have fuse boxes. A fuse is a short piece of metal that melts when too large of a current passes through it.
Fuses must be replaced when overloaded.

20. Home Electricity – Circuit Breakers
Newer buildings have circuit breakers. A circuit breaker is an automatic switch that opens when the current reaches a certain value.
Circuit breakers
can be switched
back on, just like
a light switch.

21. Home Electricity – GFI or GFCI
Newer houses also have ground-fault circuit interrupters in kitchens and bathrooms. They can detect any difference in current flow and stop it to prevent some electrocutions.
The individual outlet will have a
“test” button and a “reset” button

22. Homework Read Chapter 23 Page 636 #36-47, 57-63, 77-81
Find out if your home has a fuse box or a circuit breaker, and if it has ground-fault interrupters.
If possible, have a parent/guardian show you your fuse box or circuit breaker
Optional advanced reading: OpenStax Chapter 21