PHY121: Electric Circuits - Series Circuits

Study Notes

A series circuit is formed when resistors are connected end to end, with the same current flowing through each resistor.
The equivalent resistance of a series circuit is the sum of the individual resistances: Req = R1 + R2 + R3.
The equivalent resistance of a series circuit is greater than the greatest resistance of any individual resistor.
Connecting two identical resistors in series produces an equivalent resistance that is twice the individual resistances.

Resistors connected in series have the same current flowing through each resistor.
Resistors connected in parallel have the same voltage across each resistor.
In a parallel circuit, the electrons have multiple paths through which they can flow.

Kirchhoff's Voltage Law (KVL) states that the sum of the voltage changes around a closed loop is zero.
Kirchhoff's Current Law (KCL) states that the algebraic sum of the currents entering a junction is equal to the sum of the currents leaving that junction.

To analyze a circuit, break it down into smaller sub-circuits that are either series or parallel.
Replace resistors in parallel with their equivalent resistance.
Use Kirchhoff's laws and Ohm's law to determine branch voltages and currents.

A junction is a point in a circuit where two or more conductors meet, also known as a node or branch point.
A branch represents a single element in a circuit, such as a resistor, current source, or voltage source.
A loop is a collection of branches that form a closed conducting path.