Electrical Conductance
Understanding electrical conductance and its relationship with resistance.
What is Electrical Conductance?
Electrical conductance is a measure of how easily electric current flows through a material. It is the reciprocal of electrical resistance. The SI unit of electrical conductance is the Siemens (S), formerly known as the mho (ohm spelled backward).
Relationship with Resistance
Where:
• G = Conductance (Siemens, S)
• R = Resistance (Ohms, Ω)
Factors Affecting Conductance
Since conductance is the reciprocal of resistance, the factors affecting resistance also affect conductance, but in the opposite way:
- Material: Materials with low resistivity (good conductors) have high conductance.
- Length: The longer the conductor, the lower its conductance.
- Cross-sectional Area: The larger the cross-sectional area of the conductor, the higher its conductance.
- Temperature: For most conductors, conductance decreases with increasing temperature.
Common Conductance Values
| Material | Approximate Conductance (S) for a standard wire | Classification |
|---|---|---|
| Copper | Very High | Conductor |
| Aluminum | High | Conductor |
| Nichrome | Low to Medium | Resistor Material |
| Silicon | Very Low | Semiconductor |
| Glass | Extremely Low | Insulator |
Frequently Asked Questions
What is the difference between conductance and conductivity?
Conductance is a property of a specific object (like a wire) that depends on its material, length, and cross-sectional area. Conductivity is an intrinsic property of the material itself, independent of its shape or size.
Why is conductance important?
Conductance is important in understanding how easily current flows through different parts of a circuit. It is particularly useful in analyzing parallel circuits, where conductances add up directly.