All power supplies contain some internal resistance when current is flowing due to the thermal energy produced as charges move.
If a battery with no internal resistance was short circuited by a wire of zero resistance where would the energy go? Some questions can't be answered because the situation is impossible.
Key Concepts
Use quizzes to practise application of theory.
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What is the value of V1?
No current so no pd across the internal resistance.
What is the value of V2?
No current so all potential dropped across switch.
What is the value of V1 when the switch is closed?
total R = 10 Ω so current = 1 A pd across internal resistance = 1 V so terminal pd = 9 V
What is the value of V2 when the switch is closed?
closed switch has zero resistance so no pd.
How much of Internal resistance have you understood?
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