potentiometer

what is potentiometer

  potentiometer is a potential divider or we can also say that it is manually adjustable resister with three terminal.Two terminals are connected to resistive element and third one is connected to wiper.wiper position is determines the output voltage.

potentiometer has three terminals first and third terminal are connected to a resistive element which has different carbon composition.A resistive element is nothing but a potential wire which possesses some specific value of resistance.this resistive element mould like a circle. in between this, a shaft which is attached with a wiper type link which is  rotates over  the resistive element.this wiper type link is responsible to change in resistance and according to this voltage will also change.
construction is also shown in figure below.
potentiometer1 potentiometer

TYPES OF POTENTIOMETER ACCORDING TO CONSTRUCTION

1.LINEAR
2.ROTARY 
3. RHEOSTAT

LINEAR
linear potentiometer  is an instrument used to measure the potential different. it consist of 10meter wire of maganin or constantan which is stretched in ten segment each of one meter length.

principle of the potentiometer
it is basically consist of a battery  and a potentiometer wire of 1m length . the positive and negative terminal of the battery are connected to the the ends A and B of the potentiometer wire.

                                 A key is also allow between the circuit to make the circuit open and close. a steady current is flowing through the circuit. this  basic circuit is known as primary circuit. the primary cell is connected with the positive terminal of the potentiometer.
the negative terminal of the cell is connected with the jokey through the galvanometer.this circuit is known as secondary circuit.if the potential difference between the A terminal of the potentiometer wire and the jokey(point C) is same as the emf of the cell then this length(AC) is known as the balancing length.in this situations the deflection shown by the galvanometer is zero.

if the balancing length is L then the potential different is  equal to IRL
E = IRL
where E is the potential difference between AC length
I is the current flow through the primary circuit
L is the length between the A
here we can easily see that the current and the resistance is equal and only length of AC is changing so potential difference is directly proportional to the length.

p23pot1 potentiometer

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