Chapter 7: Direct Current Circuits

**average current formula**

**Resistance**

is the extent to which a resistor impedes the passage of electric current

**Resistance formula**

**Resistivity**

is a property of what molecules a material consists of and how the molecules that constitute a material are bound together

The voltage is provided in a circuit by some source, which is typically a **_______**for direct current circuits.

**battery**

**Circuit**

A conducting pathway connecting terminals of a voltage source in an electric current.

**Direct current**

Current that always travel in the same direction through the pathway.

Circuits contains three basic elements:

batteries, resistors, and connecting wires

**resistors**

devices that control the current

resistor symbol in a circuit diagram

batteries symbol in a circuit diagram

**Series circuit**

arranged one after the other, all share the same current and if the total voltage drop across them is equal to the sum of the individual voltage drops across each

**Parallel circuit**

side-by-side, current that flows through one of the resistors cannot flow through the other because there is a junction before the resistors

\

resistors in series

resistors in parallel

**Loop Rule**

The sum of the potential differences (positive and negative) that traverse any closed loop in a circuit must be zero.

**Junction Rule/ Node Rule**

The total current that enters a junction must equal the total current that leaves the junction.

For a capacitor, the capacitance is given by