1. Introduction to Electric Circuits

2. Closed Circuit—a complete conductive pathway exists between high and low potential. Open Circuit—no complete conductive pathway between high and low potential. Short Circuit—a compete conductive pathway exists between high and low potential, but one or more components is by-passed.

3. Three Parameters of a Circuit
Current—the rate of flow of electric charge
Symbol: I
Units: amperes (amps) A
1 A = 1 C/s
Equation: I = q/t
Example: It takes 5.00 s for 4.80 x electrons to pass a point in a circuit. Find the current.

4. Conventional flow vs. electron flow
In almost all modern-day applications, it is accepted that charge carriers in a circuit move from the positive potential toward the negative. This is called conventional current flow. In reality, we know that electrons—the true charge-carriers in a circuit—move from negative potential toward the positive potential.

5. Potential Difference—the difference in electric potential between two points.
Symbol: ΔV
Units: volts (V)
Provided by battery, generator, solar cell, etc.

6. Resistance—a restriction of charge movement; transforms electrical energy into other forms.
Symbol: R
Units: ohms (Ω)
Several factors affect the amount of resistance in a device:

7. Resistance (continued)
Length—resistance increases as length increases.
Cross-sectional Area—resistance increases as cross-sectional area decreases.
Temperature—resistance typically increases as temp. increases.
Material—resistance varies with the type of material used.