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Question
Solve the following problem.
A battery of emf 12 V and internal resistance 3 Ω is connected to a resistor. If the current in the circuit is 0.5 A,
- Calculate resistance of resistor.
- Calculate terminal voltage of the battery when the circuit is closed.
Sum
Solution
Given: E = 12 V, r = 3 Ω, I = 0.5 A
To find: a. Resistance (R)
b. Terminal voltage (V)
Formulae: i. E = I (r + R)
ii. V = IR
Calculation: From formula (i),
E = Ir + IR
∴ R = `("E"-"Ir")/"I"`
= `(12-0.5xx3)/0.5`
= 21 Ω
From formula (ii),
V = 0.5 × 21
= 10.5 V
- The resistance of a resistor is 21 Ω.
- The terminal voltage of the battery when the circuit is closed is 10.5 V.
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Electromotive Force (emf)
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Chapter 11: Electric Current Through Conductors - Exercises [Page 220]
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