When resistors are connected in series, the current through each resistor is the same ... _{1}+\frac{1}{R}_{2}\) To calculate the total resistance of three resistors connected in parallel ...

A LED takes a current of \(12.5 mA\) when the voltage across it is 2 V. Draw a suitable circuit and calculate the value of the series resistor needed to operate the LED from a \(9 V\) battery.