Multiple choice

A battery of emf 10 V and internal resistance 3 is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor?

  1. 5 ohm

  2. 2 ohm

  3. 17 ohm

  4. 0.05 ohm

  5. 20 ohm

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C Correct answer
Explanation

The relation for current using Ohm’s law is I = E / R + r R + r = E / I = 10 / 0.5 R + r = 20 ohm R = 20 - 3 R = 17 ohm