By error,a student places a moving-coil voltm | vedclass

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(D) An ideal voltmeter has an extremely high resistance,approaching infinity. When connected in series with a circuit,it acts as an open circuit becau

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$12$

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(D) An ideal voltmeter has an extremely high resistance,approaching infinity. When connected in series with a circuit,it acts as an open circuit because it draws negligible current.In the given circuit,the total resistance of the circuit becomes $R_{total} = R_{resistor} + R_{voltmeter} \approx \infty$.The current flowing through the circuit is $I = \frac{E}{R_{total}} = \frac{12}{4 + \infty} \approx 0 \ A$.The voltage drop across the $4 \ \Omega$ resistor is $V_{resistor} = I 	imes R = 0 	imes 4 = 0 \ V$.According to Kirchhoff's voltage law for the loop,the sum of potential drops must equal the $EMF$ of the battery: $V_{resistor} + V_{voltmeter} = E$.Substituting the values: $0 + V_{voltmeter} = 12 \ V$.Therefore,the voltmeter reading will be $12 \ V$.

By error,a student places a moving-coil voltmeter $V$ (nearly ideal) in series with the resistance in a circuit in order to read the current,as shown. The voltmeter reading will be ............ $V$.

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