Why is potentiometer better than voltmeter

Difference between a potentiometer and a voltmeter

The Potentiometer and the voltmeter both are the Voltmeter. The significant difference between the two is that Potentiometer measures the emf the circuit during Voltmeter measures the End clamp tension the circuit. The other differences between the potentiometer and voltmeter are explained in the comparison table below.

The potentiometer works on the principle of the comparison method. It compares the unknown voltage sources with the standard voltage source. When their voltages are equal, the galvanometer shows the zero deflection. The voltmeter is connected in parallel to the circuit whose voltage is to be measured.

Contents: potentiometer versus voltmeter

  1. Comparison table
  2. definition
  3. Main differences
  4. Conclusion

Comparison table

Basis for comparison Potentiometer Voltmeter
definition It is an instrument for measuring the unknown voltage.Type of measuring devices for voltage measurement.
Measured value Exactly CA
sensitivity High Low
Device type Zero deflection typeDeflection type
resistanceInfinite Very high but measurable

Definition of potentiometer

The potentiometer is the three terminal device that is used to measure the unknown voltage source by comparing it to the known voltage. The standard source supplies the known voltage.

The potentiometer has seven thin wires parallel to each other. One end of the wire is attached to each other with the help of the copper strips. The copper strips convert the seven parallel wires into one. The battery and variable resistor are placed in parallel with the EMF source.

One end of the unknown and known source is connected in parallel. The other end of the sources is connected to the two-way switch. The galvanometer is connected to the other end of the switch. The jockey, which is connected to the galvanometer, is moved on the wire until the galvanometer shows zero deflection.

Definition of voltmeter

The voltmeter measures the voltages between any two points in a circuit. The voltmeter has a high internal resistance, which is why the device draws little current.

The function of the voltmeter depends on the high internal resistance. The voltmeter is of two types; H. The analog or digital voltmeter. It is always connected in parallel to the circuit.

The current through the measured variable source flows through the high-resistance circuit of the counter. With an analog voltmeter, the value of the unknown voltage is known by the product of the resistance, and the current flows through the circuit.

Main differences between potentiometer and voltmeter

The main differences between potentiometers and voltmeters are listed below.

  1. The potentiometer is an instrument used to measure emf, while the voltmeter is a type of measuring device that measures the terminal voltage of the circuit.
  2. The potentiometer measures exactly the potential difference due to zero internal resistance. The voltmeter, on the other hand, has a high internal resistance, which causes the measurement error. So the voltmeter roughly measures the voltage.
  3. The sensitivity of the potentiometer is very high, i. H. It can measure small potential differences between the two points. The voltmeter has a low sensitivity.
  4. The potentiometer uses the instrument of zero deflection while the voltmeter uses the instrument of deflection.
  5. The potentiometer has an infinite internal resistance, while the potentiometer has a high measurable resistance.


The potentiometer and voltmeter both measure EMC in volts The potentiometer is used in a circuit where the exact voltage reading is required. The voltmeter is used for an approximate calculation.