## Potentiometers

Resistors provide a fixed value of resistance that blocks or resists the flow of electrical current around a circuit, as well as producing a voltage drop in accordance with Ohm’s law. Resistors can be manufactured to have either a fixed resistive value in Ohms or a variable resistive value adjusted…

## Resistivity

Ohms Law states that when a voltage (V) source is applied between two points in a circuit, an electrical current (I) will flow between them encouraged by the presence of the potential difference between these two points. The amount of electrical current which flows is restricted by the amount of…

## Varistor Tutorial

Unlike the fuse or circuit breaker which offers over-current protection, the varistor provides over-voltage protection by means of voltage-clamping in a similar way to the zener diode. The word “Varistor” is a combination of the words VARI-able resi-STOR used to describe their mode of operation way back in their early days of…

## Resistor Tutorial Summary

The job of a Resistor is to limit the current flowing through an electrical circuit. Resistance is measured in Ohm’s and is given the symbol Ω Carbon, Film and Wirewound are all types of resistors. Resistor colour codes are used to identify the resistance and tolerance rating of small resistors. The BS1852 Standard uses letters…

## Resistor Colour Code Wheel

Resistor colour codes can sometimes be a little confusing until you understand how they work. But once you get the hang of them it becomes easier to read the values of those simple colour coded bands. There is a lot of information both online and on this Electronics Tutorials website…

## Resistor Power Rating

When an electrical current passes through a resistor due to the presence of a voltage across it, electrical energy is lost by the resistor in the form of heat and the greater this current flow the hotter the resistor will get. This is known as the Resistor Power Rating. Resistors are…

## Resistors in AC Circuits

In the previous tutorials we have looked at resistors, their connections and used Ohm’s Law to calculate the voltage, current and power associated with them. In all cases both the voltage and current has been assumed to be of a constant polarity, flow and direction, in other words Direct Current or DC. But…

## Potential Difference

Unlike current which flows around a closed electrical circuit in the form of electrical charge, potential difference does not move or flow it is applied. The unit of potential difference generated between two points is called the Volt and is generally defined as being the potential difference dropped across a fixed resistance…

## Resistors in Series and Parallel

In the previous tutorials we have learnt how to connect individual resistors together to form either a Series Resistor Network or a Parallel Resistor Network and we used Ohms Law to find the various currents flowing in and voltages across each resistor combination. But what if we want to connect…

## Resistors in Parallel

Unlike the previous series resistor circuit, in a parallel resistor network the circuit current can take more than one path as there are multiple paths for the current. Then parallel circuits are classed as current dividers. Since there are multiple paths for the supply current to flow through, the current…

## Resistor Colour Code

There are many different types of Resistor available which can be used in both electrical and electronic circuits to control the flow of current or to produce a voltage drop in many different ways. But in order to do this the actual resistor needs to have some form of “resistive” or “resistance”…

## Resistors in Series

Individual resistors can be connected together in either a series connection, a parallel connection or combinations of both series and parallel, to produce more complex resistor networks whose equivalent resistance is the mathematical combination of the individual resistors connected together. A resistor is not only a fundamental electronic component that…