Lecture Notes: Electrical Circuits

Types of Electrical Circuits

• Series Circuit

  • Components connected end to end.
  • Form a simple loop for current to flow.
  • Voltage: Total voltage is shared between components.
  • Current: Same current flows through each component.
  • Resistance: Total resistance is the sum of individual resistances.

• Parallel Circuit

  • Components connected side by side.
  • Current divides and flows through different paths.
  • Voltage: Same voltage across each component.
  • Current: Total current is the sum of currents through each component.
  • Resistance: Total resistance is less than the smallest individual resistor.

Key Concepts

• Voltage

  • Measure of electrical push from the battery.
  • Measured in volts (joules per coulomb).
  • Voltmeters are connected in parallel.

• Current

  • Flow of negatively charged electrons.
  • Measured in amperes (coulombs per second).
  • Ammeters are connected in series.

• Resistance

  • Opposition to current flow.
  • Measured in ohms (Ω).
  • Higher resistance means more difficulty for current to flow.

Calculating Resistance

• Series Resistors

  • Total resistance: Sum of individual resistances.
  • Example: Two resistors of 3 Ω each in series = 6 Ω.

• Parallel Resistors

  • Use formula: (1/R = 1/R_1 + 1/R_2).
  • Example: Two resistors of 3 Ω in parallel = 1.5 Ω.
  • Example: (1/r = 1/10 + 1/5 = 3/10), so (r = 3.33 Ω).

Practical Applications

• Voltage and Current Measurements

  • Example: Four cells each providing 1.5 V.
  • Calculate potential difference and current through components.
  • Current through lamp: 0.20 A, resistor: 0.10 A.

• Circuit Examples

  • Resistance calculation and understanding of series vs parallel configurations.

Summary

• Understanding the difference between series and parallel circuits.
• Calculating resistance in different circuit configurations.