Here we
consider circuits with an AC power supply and all three
fundamental elements, a resistor, an inductor and a
capacitor. The same current flows through each element at
every instant in time. The voltages across the four
elements must sum to zero when travelling around the loop
at any instant as well. Although the voltages across all
the elements rise and fall with the same frequency, they
do not all have the same In the figure on the right, the voltage drop
across each element is shown as a function of time. The
green line, which is the voltage drop across the
resistor, also demonstrates the phase of the current. One
can see that V_{c
}as it keeps rising until the current is no
longer forward. This is because it is proportional to the
charge which grows as long as the current is positive.
Thus V_{L }and
V_{c }are 180
degrees out of phase, which means they simply have
opposite signs.The and C.
The impedance R (derivation
in next page) can
be thought of as the AC analog to resistance.ZThe impedance is at a
minimum when the |