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⚾️honors physics review

Conductance

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Conductance is a measure of a material's ability to allow the flow of electric current. It is the reciprocal of resistance and represents the ease with which electric charge can move through a conductor, such as a wire or a resistor in a parallel circuit.

5 Must Know Facts For Your Next Test

  1. Conductance is measured in Siemens (S), which is the reciprocal of Ohms (Ω), the unit of resistance.
  2. The conductance of a resistor in a parallel circuit is the reciprocal of its resistance, and the total conductance of the parallel circuit is the sum of the conductances of the individual resistors.
  3. Conductance is an important parameter in the analysis and design of parallel circuits, as it determines the distribution of current among the different branches.
  4. Increasing the conductance of a branch in a parallel circuit will increase the current flowing through that branch, while decreasing the current in the other branches.
  5. The relationship between conductance, resistance, and current in a parallel circuit is governed by Ohm's Law and the principle of conservation of charge.

Review Questions

  • Explain how conductance relates to the flow of electric current in a parallel circuit.
    • Conductance is a measure of a material's ability to allow the flow of electric current. In a parallel circuit, the conductance of each branch determines the distribution of current among the different branches. The branch with higher conductance (lower resistance) will have a larger current flowing through it, while the branch with lower conductance (higher resistance) will have a smaller current. The total conductance of the parallel circuit is the sum of the conductances of the individual branches, and this total conductance determines the overall current flow in the circuit.
  • Describe how the relationship between conductance, resistance, and current in a parallel circuit is governed by Ohm's Law.
    • According to Ohm's Law, the current through a conductor is directly proportional to the voltage applied across it and inversely proportional to the resistance of the conductor. In a parallel circuit, the voltage is the same across each branch, but the current divides among the different branches based on their respective conductances. The branch with higher conductance (lower resistance) will have a larger current flowing through it, while the branch with lower conductance (higher resistance) will have a smaller current. The total current in the parallel circuit is the sum of the currents in the individual branches, and this total current is determined by the total conductance of the circuit, which is the sum of the conductances of the individual branches.
  • Analyze the impact of changing the conductance of a branch in a parallel circuit on the distribution of current and the overall circuit behavior.
    • Increasing the conductance of a branch in a parallel circuit will increase the current flowing through that branch, while decreasing the current in the other branches. This is because conductance is the reciprocal of resistance, and a higher conductance means a lower resistance. According to Ohm's Law, a lower resistance in a branch will result in a higher current through that branch, as the voltage across the branch remains the same. Conversely, decreasing the conductance of a branch will reduce the current flowing through that branch, and the current will be redistributed among the other branches in the parallel circuit. This change in current distribution can impact the overall circuit behavior, such as the power dissipation in each branch and the overall efficiency of the circuit.