# When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit.

When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.

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Resistance (R) of a resistor is given by Ohm's law as,VIR
RV/I
Where,
Potential difference, V= 12 V
Current in the circuit, I= 2.5 mA = 2.5 x 10-3 A

$$R=\frac{12}{2.5\times 10^{-3}}=4.8\times 10^3=4.8 K\Omega$$

Therefore, the resistance of the resistor is 4.8 kΩ