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.

Explanation

In this problem, the current is given in the units of milliamperes (mA), so the current is to be converted into the units of amperes (A) by dividing the given milliamperes value by 1000.
Here, Potential difference, `V = 12V`
Current, `I = 2.5 mA`
`= (2.5)/(1000)A`
`=0.0025 A`
And, Resistance, `R = ?` (To be calculated)
From Ohm's law:
So, `(12)/(0.0025) = R`
And, Resistance, `R = 4800 Omega` (or `4.8 k Omega)`