A potentiometer is a common component in electronic devices, which is widely used in various circuit control systems. It controls the voltage by adjusting the resistance in the circuit.

In this article, let’s discuss in detail what a potentiometer is, its working principle and application, and its difference with a rheostat.

1.    What is a potentiometer?

First, what is a potentiometer? A potentiometer is a common electronic component, often called a "pot", used to precisely control voltage or current in a circuit.

The core part of a potentiometer is a variable resistor, which is usually equipped with three terminals: two fixed terminals and an adjustable sliding terminal (also called a wiper). By rotating the control shaft of the potentiometer, people can adjust the position of the wiper between the two fixed terminals, thus flexibly changing the resistance value. This design makes the potentiometer ideal for use in situations requiring precise adjustment.

The Potentiometer Diagram/ Symbol

In a circuit diagram, the symbol for a potentiometer is usually represented as a resistor with an arrow. This symbol consists of two parts: a rectangular or jagged line representing a fixed resistance element, and a diagonal arrow that intersects the resistance element. The two terminals of the resistance element are connected with two fixed terminals, representing the poles of the potentiometer, and the arrow points to a certain position of the resistance element, indicating the sliding contact of the potentiometer.

The Potentiometer Formula

The operation of a potentiometer can be described using the voltage divider formula. When the total resistance of the potentiometer is R, the wiper divides this resistance into two parts: R ₁ and R ₂ . These two resistances add up to the total resistance, so R ₁ + R ₂=R. The input voltage Vin is applied across the two ends of the potentiometer, and the position of the wiper determines the values of R ₁ and R ₂, which, in turn, affects the output voltage Vout.

The output voltage at the wiper, Vout , can be calculated using the following voltage divider formula:

This potentiometer formula can help us calculate the potential difference at any given point along the resistive element.

Types of Potentiometers

With the development of technology, electronic devices have higher and higher requirements for components. Therefore, people have designed various types of potentiometers according to different needs.

The following are several common potentiometer types: rotary potentiometer, linear potentiometer and digital potentiometer.

2.    How does a potentiometer work?

How does a potentiometer work? It’s very easy. It adjusts the output voltage or resistance value by changing the position of the sliding contact on the resistance element.

When the slide moves along the resistance element, the potentiometer changes the resistance of the two parts of the circuit, thus changing the output voltage. By adjusting the position of the slide, the resistance ratio of the two parts can be adjusted, which directly affects the output voltage.

As we can see from the potentiometer diagram above, the movement of the slide splits the total resistance into two parts, enabling it to function as a voltage divider or variable resistor.

For example, in the volume control knob, rotating the potentiometer can adjust the resistance to change the volume. In a tuning circuit, a potentiometer adjusts the tuning frequency of a radio receiver by changing the voltage in certain sections.

3. Potentiometer vs rheostat

What is rheostat?

From the above, we learned that the potentiometer has three terminals and can also be used as a voltage divider. Unlike a potentiometer, a rheostat is a two-end device that adjusts the current in the circuit by changing the resistance value.

What's the difference between a potentiometer and a rheostat

A potentiometer and a rheostat are mainly different in use. The potentiometer is mainly used to control voltage, while the rheostat is used to control current.

At the same time, the potentiometer can also be used as a variable voltage divider, and the rheostat can be used as a resistor to adjust the current flow.

Structurally, the slide of a potentiometer divides the resistance element into two parts, while in a rheostat, the slide controls the circuit only by adjusting the total resistance.

Conclusion

All in all, a potentiometer is a crucial component in electronic circuits. It offers precise control over voltage by adjusting resistance. Its basic working principle, symbol, and formula show us how it can divide voltage or act as a variable resistor. With various types available, potentiometers are widely used in applications such as audio control, light dimming, and tuning circuits. When comparing potentiometers vs rheostats, the primary difference is that potentiometers control voltage, while rheostats control current. Understanding these differences is essential for selecting the right component for your circuit.