11.5.B—Describe a circuit with resistive wires and a battery with internal resistance

Describe a circuit with resistive wires and a battery with internal resistance.

• Ideal batteries have negligible internal resistance. Ideal wires have negligible resistance.
  • i. The resistance of wires that are good conductors may normally be neglected, because their resistance is much smaller than that of other elements of a circuit.
  • ii. The resistance of wires may only be neglected if the circuit contains other elements that do have resistance.
  • iii. The potential difference a battery would supply if it were ideal is the potential difference measured across the terminals when there is no current in the battery and is sometimes referred to as its emf (E).
• The internal resistance of a nonideal battery may be treated as the resistance of a resistor in series with an ideal battery and the remainder of the circuit.
• When there is current in a nonideal battery with internal resistance r, the potential difference across the terminals of the battery is reduced relative to the potential difference when there is no current in the battery. Derived equation: 73