# 2 Basic theory of electrical circuits

Now that you have seen some of the applications of electronics through the sensing–logic–actuation cycle, let’s return to fundamentals.

In what follows, you will look at one of the most important components in electronics: the resistor. This is an example of a passive component – a component that does not supply its own electricity. First, however, let’s review some basic electrical quantities.

Note that the term DC means direct current such as that in a circuit powered by a battery. In contrast, the term AC means alternating current as provided by electrical mains suppliers.

OpenLearn - An introduction to electronics
Except for third party materials and otherwise, this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence, full copyright detail can be found in the acknowledgements section. Please see full copyright statement for details.