Whatever the field of human activity-domestic or scientific, work or
leisure-it is likely that some knowledge of the behaviour of electrical
circuits is required to keep the processes moving, the wheels turning.
In many cases, a knowledge of Ohm's law may suffice. In others, an
understanding of more complex relationships may be necessary. In this
book an attempt is made to provide, in a concise manner, an introduction
to the main methods of treating electrical networks, whether they be
carrying direct (de) or alternating (ac) electrical currents. Clearly,
the range of possible circuits is vast so that the simplifications which
are demonstrated in the pages that follow are of great importance to the
student. However, to gain the fullest benefit from such a concise
presentation, the student must devote some time to the exercises which
are provided in Appendix B. The units used throughout the book are those
of the International System (or SI). The various quantities which are
introduced-such as current and potential and resistance-are summarized
in Appendix A together with the symbols used to represent them, the unit
associated with each quantity and the formula used to derive that unit
from four fundamental or MKSA units.