
87
and then take another look at one of the forms of expressing Ohm's
law:
we see they are the same except that \/2nf C takes the place of R in
the role of limiting the current in the circuit. So, although \/2nf Cis
quite a different thing physically from resistance, for purposes of
calculation it is of the same kind, and it is convenient to reckon it in
ohms.
To distinguish it from resistance it is named reactance. To
avoid having to repeat the rather cumbersome expression \/2nf C,
the special symbol X has been allotted. The Ohm's law' for the
Fig. 6.1 circuit can therefore be written simply as
For example, the reactance of a 2 μΡ capacito ...