Three Chapter 5

Resistance in Series and Parallel

• The amount of current through branches of a circuit, and the differences in electric potential between points in a circuit depends upon:
  • Kifchhoff's Voltage Law (KVL)
  • Kirchhoff's Current Law (KCL)
  • Ohm's Law
• No matter how complicated the circuit, all can be analyzed by using the above three laws.
• Analysing a circuit means to determine
  • the current through it
  • the potential difference across it
  • the value of the resistances
• When several resistances are present, analysis often means determining the total resistance present.

Resistance in Series

• Resistance in Series means that resistors are placed one after the next so that electrons must flow through each and every resistor.
• Consider

• Question : What is the equivalent resistance (R_s diagram B) that could replace the three resistors R₁, R₂, and R₃ (diagram A)?
  • Note that the potential difference across the source is V₀ and the current leaving the source is I₀.

Resistance in Parallel

• Resistance in parallel means that resistors are placed so that electrons have a choice as to which resistor to flow through.
• Consider:

• Question - What is the equivalent resistance (R_p Diagram B) that could replace the three resistors R₁, R₂, and R₃ in diagram A?

Electric Circuit Analysis

• Given this information you should be able to analyze any circuit provided enough information is given.
• The steps taken depend on the information givem
  • There is no standard method due to the great variety of possible circuits.

December 31, 2013