The potential difference between the terminals of a battery in an open circuit is 2.2 V. When it is connected across a resistance of 5.0 Ω, the potential falls to 1.8 V. What is the internal resistance of the battery?
Correct answer: D. 1.11 Ω
- A. 9.11 Ω
- B. 2.11 Ω
- C. 3.11 Ω
- D. 1.11 Ω
- E. 0.11 Ω
Explanation
To find the internal resistance of the battery, we can use the formulas:1. The emf, E, is the open-circuit voltage: E = 2.2 V.2. When the battery is connected to a resistance of 5.0 Ω, the terminal voltage V = 1.8 V.Using Ohm's Law, V = IR, where I is the current flowing through the external resistance. Therefore, I = V/R = 1.8 V / 5.0 Ω = 0.36 A.The internal resistance, r, can be found using the formula E = V + Ir, so 2.2 V = 1.8 V + 0.36 A * r.Solving for r gives r = (2.2 V - 1.8 V) / 0.36 A = 1.11 Ω.The correct answer is 1.11 Ω.Other Options:Option A (9.11 Ω), Option B (2.11 Ω), Option C (3.11 Ω), and Option E (0.11 Ω) are incorrect as they result from miscalculations or misunderstandings of the relationship between emf, internal resistance, and external resistance.
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About Current Electricity
Steady current relates charge flow to potential difference, resistance and resistivity, including how temperature changes a conductor's resistance. Sources with internal resistance have terminal voltage below their emf when delivering current, and maximum power output occurs under a specific load condition rather than at zero resistance.
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