A Guide to Electrical Resistors and their Working Principles

The central element that defines an electrical resistor’s performance is the electrical resistance of a component. This property governs how much the device can inhibit the charge flow through a circuit.

Electrical resistance is measured in ohms (Ω), where 1Ω permits the transmission of a single ampere of current when exposed to a potential difference of a single volt. This definition refers to Ohm’s Law, which states a DC circuit current is inversely proportional to its resistance and directly proportional to its voltage. Something to be mindful of when using this well-established rule is that for it to apply, all other factors must be equal. In certain situations, Ohm’s Law is also applicable to AC circuits.

In this article, TT Electronics explains the working principles of electrical resistors in more detail.

What are Electrical Resistors?

Electrical resistors are commonly available in an array of technologies with different mountings and packages. The most common types of electrical resistors are fixed resistors.

Fixed electrical resistors display an unvarying and pre-defined electrical resistance that cannot be adjusted. The overall impedance is subject to peripheral singularities like stray capacitance and inductance. These are both usually alleviated by the type of material used to impede the current’s flow and by the methods of adjustment and termination.

Some of the earliest fixed resistors had their foundation in carbon composition technology. There is a mixture of fine carbon particles and a binding material like clay inside a carbon composition resistor’s packaging. These display broad electrical resistance characteristics with reduced tolerance and temperature coefficients of resistance. However, they are reliable in the regulation of currents and are able to withstand pulses and energy surges very well.

Carbon composition electrical resistors have generally been replaced by devices produced through film deposition. These devices make use of a central, ceramic core coated by a functional material such as carbon, tantalum nitride (TaN), or a metallic alloy such as nichrome (NiCr). The surface mount area is dominated by thick-film chip resistors. Among the cheapest electrical resistors, they also enable designers to reach the highest electrical resistances.

Wirewound electrical resistors offer another option over carbon composition and film-type devices. They are made by coiling a wire around an insulating core. They are often used in line input circuits and as fuses, thanks to their failsafe tolerance to surges. As a whole, they can withstand higher current surges than alternative resistors and are very suitable for high-power applications.

Electrical Resistors from TT Electronics

TT Electronics offers a huge range of almost 1,000 distinct electrical resistors. We cover every mounting type, from heat sink, adhesive and solder resistors, to wire-bound and through-hole resistors.


This information has been sourced, reviewed and adapted from materials provided by TT Electronics plc.

For more information on this source, please visit TT Electronics plc.


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