Voltage Divider edit
If two circuit elements are in series, there is a voltage drop across each element, but the current through both must be the same. The voltage at any point in the chain divides according to the resistances. A simple circuit with two (or more) resistors in series with a source is called a voltage divider.
Figure A: Voltage Divider circuit.
Transfer Function of Voltage Divider edit
Consider the circuit in Figure A. According to KVL the voltage is dropped across resistors and . If a current i flows through the two series resistors then by Ohm's Law.