Lecture Notes: Series Circuits

Key Concepts

• Difference between Series and Parallel Circuits
  • Series Circuit: Single loop where components are connected one after another.
  • Parallel Circuit: Contains more than one loop.

Series Circuit Characteristics

• Circuit Continuity

  • All components connected in a single loop.
  • If one component is disconnected or broken, the entire circuit stops working.
  • Practical use is limited due to this downside.

• Potential Difference (Voltage)

  • The total voltage of the cell/battery is shared across all components.
  • Equation: Total voltage = Sum of individual component voltages.
  • Example:
    • Battery potential difference = 12 volts.
    • If two lamps:
      • Voltage across first lamp + second lamp = 12 volts.
      • If lamp 1 = 8 volts, then lamp 2 = 4 volts (8 + 4 = 12).
      • If lamps are identical, voltage = 6 volts each (12/2 = 6).

• Current

  • Same throughout the circuit, regardless of location.
  • Measured using an ammeter, placed in series.
  • Current (I) can be calculated using Ohm’s Law: I = Total potential difference / Total resistance.

• Resistance

  • Total resistance is the sum of individual resistances of all components.
  • Example:
    • If lamp 1 = 4 ohms, lamp 2 = 2 ohms.
    • Total resistance = 4 + 2 = 6 ohms.

• Calculating Current Example

  • Using Ohm’s Law: Current = Potential difference / Resistance.
  • Example:
    • Battery = 12 volts, Total resistance = 6 ohms.
    • Current = 12 / 6 = 2 amps.

Voltage Across Components

• Using Current and Resistance

  • Calculate voltage across a specific component.
  • Example:
    • Lamp resistance = 2 ohms, Current = 2 amps.
    • Voltage = Current x Resistance = 2 x 2 = 4 volts.

• Alternative Methods

  • Subtract known voltage from total to find unknown voltage.
  • Use a voltmeter in parallel:
    • Example: Voltmeter reading = 8 volts.

Ohm’s Law and Voltage Distribution

• Components with greater resistance have a higher share of voltage.
• More force required to push charge through areas of higher resistance.
• Example: 4 ohm resistor has 8 volts, whereas 2 ohm resistor has 4 volts.

Conclusion

• Understanding series circuits involves knowing component connectivity, calculation of voltage, current, and resistance.
• Ohm’s Law is crucial to perform these calculations and understand the distribution of electrical parameters across the circuit.