Potential divider and potentiometerCopy

Learning Objectives

• Describe the action of a variable potential divider (potentiometer)

Contents to learn

Potential divider or Potentiometer
Resistors in series, connected across a source of voltage, used to obtain a desired fraction of the total supplied voltage is called potential divider.

In the above circuit, both the resistors have the same value of resistance so provided potential will be divided equally to both of them i.e. 5V each. But if both resistors have different values then output voltage will depend upon the value of resistance of the resistor across which we are taking the output.

Potentiometer is also used as a potential divider. The symbol of potentiometer is shown below.

Consider the following diagram of potentiometer.

Fig.

As the sliding contact is moved along the resistance wire from A to B, the reading on the voltmeter gradually increases. If the voltmeter is replaced by a lamp, the brightness of the lamp increases as the sliding contact is moved from A to B. This shows how this can be used as a variable voltage supply.

When a variable resistor is used in this way, we call it a variable potential divider or potentiometer.

Rheostat is also a type of potentiometer.

Fig.