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 Electric circuit Circuit symbols Circuit diagrams Diode Diode as forward biased and reversed biased Diode as a rectifier Diode as half wave rectifier Diod as full wave rectifier Transistors Series circuits Parallel circuits Effective or equivalent resistance in series circuits Effectice or equivalent resistance in parallel circuits Advantages of connecting lamps in parallel in lighting circuits Potential divider or Potentiometer Thermistors Light dependent resistor - (L.D.R.) Input transducers Capacitors Capacitance of the capacitor One Farad Different types of capacitors Time delay circuits Relay Rectifier circuits Transistor as switch Light sensitive switch Temperature operated alarms

## 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.

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