The Potential Divider

Often we want to be able vary the voltage across a component – to dim the lights or turn the sound up or down for example. We can do this by varying the resistance in a circuit. The output voltage can be varied with a potential divider shown below. Changing the value of the variable resistor R-2 changes the output voltage V-OUT .

The total resistance in the circuit isso if the battery voltage iswe can use Ohm's Law,to get the current:

Now apply Ohm's law to the output resistorto get the output voltage

If the output resistance R-2 is reduced to zero, the output voltage is zero. V-OUT can be increased to a maximum by increasing R-2 to its largest possible value.

In practice a slightly different arrangement is often used with a sliding contact on a wire.

Resistance is proportional to length so

Comments   

#1HAMAD2017-01-07 14:40
I like it, easy explination and simple.

thanks
Admin says: I am a simple soul.

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