Potentiometer working can be explained when the potentiometer is understood. It is defined as a three-terminal resistor having either sliding or rotating contact that forms an adjustable voltage divider. In order to use the potentiometer as a rheostat or variable resistor, it should have only two terminals with one end and the wiper.
Following are the terms used to describe types of potentiometers:
1. Slider pot or slide pot: This can be adjusted by sliding the wiper right or left with a finger or thumb.
2. Thumb wheel pot or thumb pot: This can be adjusted infrequently with the help of small thumb wheel which is a small rotating potentiometer.
3. Trimmer pot or trim pot: This can be adjusted once for fine-tuning of an electric signal.
Note :
(i) Potentiometer wire : Made up of alloys of manganin, constantan, eureka.
(ii) Special properties of these alloys are high specific resistance, negligible temperature co-efficient of resistance (α). This results in invariability of resistance of potentiometer wire over a long period.
➢ Potential gradient (x) (V/m)
➢ Factors affecting 'x'
Note:
xmax or xmin on the basis of range of rheostat or resistance box (R.B.)
l1 from A then
E1 = Kl1
Where K → Potential gradient along the length of wire
Similarly cell having emf E2 is introduced in the circuit and again null point J2 is determined. If length of this null point from
A is l2 then
E2 = Kl2
Therefore
E1/E2 = l1/l2
This simple relation allows us to find the ratio of E1/E2
if the EMF of one cell is known then the EMF of other cell can be known easily
105 videos|425 docs|114 tests
|
1. What is a potentiometer? |
2. What are the applications of a potentiometer? |
3. How does a potentiometer work? |
4. Can a potentiometer be used as a voltage divider? |
5. What are the advantages of using a potentiometer? |
|
Explore Courses for NEET exam
|