Free Science Lessons: Filament Lamp Current-Potential Difference Graph

Overview

Objective: Describe and explain the current-potential difference graph for a filament lamp.
Comparison: Contrast with the graph for a resistor from a previous lesson.

Symbol: Resistors have a specific symbol used in circuit diagrams.
Function: Used in circuits to control potential difference across components.
Graph: Current through a resistor is directly proportional to the potential difference, indicating constant resistance (Ohmic conductor).
Condition: The relationship holds if the temperature remains constant.

Definition: A filament lamp contains a very fine wire, known as a filament, which is tightly coiled.
- Examples: Household filament lamps, torch bulbs.
Operation: The filament heats up when an electric current passes through, causing it to glow and emit light.
Efficiency: Being phased out due to low energy efficiency.

Setup: Similar to the resistor experiment; change potential difference and measure the current.
Graph Observation:
- Non-Proportionality: Current is not directly proportional to the potential difference.
- Reason: As the filament heats up, resistance increases.
- Atomic Activity: At high temperatures, atoms vibrate more intensely.
  - Electron Collision: Increased collisions between electrons and atoms, requiring more energy to maintain current flow.
- Graph Shape: As potential difference increases, the current increases less sharply, indicating rising resistance.
- Conclusion: Filament lamps are not Ohmic conductors.

Importance: Knowing the graph shape is crucial for exams.
Resources: Refer to additional questions in the vision workbook available through a provided link.

Learning Goals: Be able to describe and explain the filament lamp's current-potential difference graph.

Remember to review the shape of the graph for filament lamps as it is often featured in exams.