Ohm's Law Lecture Notes

Key Concepts

• Electrical Resistance

  • Property that slows down electron movement and converts electrical energy into other forms.
  • Measured in ohms (Ω) using an ohmmeter.

• Resistors

  • Components that provide specific resistance in a circuit.
  • Used to control current or voltage for electronic devices.

• Ohmic vs. Non-Ohmic Resistors

  • Ohmic Resistors
    • Resistance does not change with temperature.
    • Follows Ohm's Law (V = IR), graph is a straight line.
  • Non-Ohmic Resistors
    • Do not follow Ohm's Law.
    • Example: Light bulbs where resistance changes with temperature.

Ohm's Law

• Mathematical relationship between voltage, current, and resistance:

  [ R = \frac{V}{I} ]

  • R: Resistance
  • V: Voltage
  • I: Current

• Resistor values can be determined by:

  • Calculation.
  • Plotting experimental data and measuring the slope of the V/I graph.

Example Problem

• Problem: Calculate voltage drop across a bulb with resistance of 144 ohms and a current of 0.50 A.

• Given:

  • R = 144 Ω
  • I = 0.50 A

• Calculation:

  • [ V = I \times R = 0.50 \times 144 = 72 \text{ volts} ]

• Answer: The voltage drop across the bulb is 72 volts.