Physics Notes

Electric Circuits

Concepts:

(A detailed list of terms & objectives is available.)

Electric Circuits
Concept Summary (download the PowerPoint file)
- Series Circuits
  - Single pathway
  - Disadvantages
    - When one device fails, all fail
    - Voltage (and energy) must be shared by all devices in the circuit
  - Equivalent (total) resistance is the sum of the individual resistances
  - Total voltage equals the sum of individual voltages
  - Current = Voltage/Total resistance (Ohm's Law)
    - Ohm's Law applies to each separate device
  - Quiz on series circuits
- Parallel Circuits
  - Voltage is the same across each device
  - Ohm's Law applies separately to each branch
  - Total current is the sum of the branch currents
  - Equivalent (total) resistance decreases as the number of branches increases
    - Equivalent (total) resistance of 2 equal resistances is half the individual resistance
    - Equivalent (total) resistance of 2 parallel branches is less than the smallest resistance
  - Overloading
    - Home circuits connected in parallel
    - Total current increases as each device is added
    - Total energy supplied increases as each device is added
    - short circuits
    - fuses & circuit breakers
  - Quiz on parallel circuits
- Comparing Series and Parallel Circuits
- Compound Circuits
  - Equivalent resistance
  - Applying Ohm's Law
    - total current
    - separate components
- Analyzing Simple Circuits - a Summary

Labs & Demos:

Activity - Series & Parallel Circuits: You construct series and parallel circuits using light bulbs and observe characteristics of the circuits.
Experiment - Series & Parallel Resistances: What is the equivalent (total) resistance of two resistors in series and parallel?
Experiment - Series & Parallel Resistances: Same as above, but uses a Genecon^tm generator as a voltage source.

Supplements:

The Best From Conceptual Physics Alive (Videodisc)
- Chapter 7 - Demo: Electric Circuits - demonstrates series and parallel circuits (5:28)

Links:

CPSurf - Electric Circuits: An excellent annotated set of links keyed to your textbook.
How Power Grids Work - part of the amazing "How Stuff Works" web site
The Basics of Series and Parallel Circuits - part of the "Understandings of Consequence Project from Harvard U.
Circuit Construction Kit - This is EXCELLENT! Build your own virtual circuits. You HAVE to try this!!

last update April 8, 2008 by JL Stanbrough