1.11 Internal Resistance

Question 1

What is internal resistance?

Answer 1

Sources of emf have themselves some resistance to the electrical current that passes through them.

Question 2

What are the 2 effects of the internal resistance of a source of emf?

Answer 2

• As more current is drawn from the battery/powerpack, the voltage across the terminals of the supply falls.
• The source of emf is less than 100% efficient as energy is dissipated as heat within it.

Question 3

What is the definition of internal resistance?

Answer 3

The loss of potential difference per unit current in the source when current passes through the source.