Question

In the circuit shown below, the ammeter and the voltmeter readings are 3 A and 6 V respectively. Then the value of the resistance R is

• A. $<2\Omega$
• B. $2\Omega$
• C. $\ge 2\Omega$
• D. $>2\Omega$

Answer 1

Answer: (A)

V = iR

$R=\frac{6}{3}=2ohm$

However, for a non-ideal ammeter, resistance of ammeter is not zero and hence, measured voltage is the sum of voltages across ammeter and resistance. In other words, measured voltage(V) is more than the actual voltage across the resistor($V_R$ ) or V>$V_R$

​Hence, measured resistance (2Ω) is more than the actual resistance.

Therefore actual resistance < 2Ω.

Hence, option c is correct.