PHY121: Electric Circuits - Series Circuits

Electric Circuits

• 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.

Series and Parallel Circuits

• 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 Laws

• 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.

Circuit Analysis

• 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.

Circuit Definitions

• 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.