G10 ADV EOT-2 Exam coverage (2023-2024) With Answers (1)

Page 9: Electric Resistance in Lamps

Introduction

• The figure discusses two lamps, (A) and (B), connected to the same voltage source.

Key Concepts

• Voltage: The electrical potential difference across the lamps is the same.

• Electric Resistance (R): Resistance is a measure of the opposition to current flow in an electrical circuit.

• Power (W): Power consumed by the lamps is denoted in watts (W).

Comparison of Lamps

• Lamp Specifications:

  • Lamp (A): 100 W

  • Lamp (B): 25 W

Power and Resistance Relationship

• Lower power corresponds to higher resistance when voltage is constant.

• Using the formula:

  [ P = \frac{V^2}{R} ]

  • Rearranging gives [ R = \frac{V^2}{P} ]

Analysis

• Lamp (A) Resistance Calculation:

  • Given higher power (100 W), indicates lower resistance.

• Lamp (B) Resistance Calculation:

  • Given lower power (25 W), indicates higher resistance.

Conclusion

• Result:

  • Lamp (B) has the higher electric resistance value compared to Lamp (A).

• Additional Notes:

  • If both lamps are connected to the same voltage, and one has a higher wattage, it will have a lower resistance than the one with lower wattage.