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.

Resistance (R) of a resistor is given by Ohm's law as,V= IR R=\(\frac{V}{I} \) Where, Potential difference, V= 12 V Current in the circuit, I= 2.5 mA = 2.5 x 10-3 A $$ R = \frac{12}{2.5} × 10^{-3} = 4.8 Kilo \Omega $$