Question

In the circuit given below, the instrument B reads 0.93 and the instrument A reads 1.80 in their respective SI units.



The value of the unknown resistor will be:
(1) 0.51 Ω
(2) 1.63 Ω
(3) 1.93 Ω
(4) 19.3 Ω

Answer 1

The instrument B is an ammeter as it is connected in series and instrument B is a voltmeter as it is connected in parallel in the circuit.

Current in the circuit = Value given by instrument B = 0.93 A
Voltage across the unknown resistor = Value given by instrument A = 1.80 V

According to Ohm's law, V =IR

Or $R=\frac{V}{I}=\frac{1.80}{0.93}=1.93\text{Ω}$

Hence, the correct answer is option 3.