If there are two resistors in series across a voltage source, then the circuit is a voltage divider ... is connected across a \(9V\) battery. Calculate the voltage across one of the resistors.

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.