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Assume an ideal power supply. For a resistor, we call the ratio between peak voltage and current, the resistance, R. For capacitors and inductors, we use the term the reactance, X, for the ratio between peak voltage and current so that V = I X. This Exploration shows that for an active load like a capacitor or inductor, the reactance depends on the frequency as well (voltage is given in volts, current is given in amperes or milliamperes (note graph labels), capacitance is given in farads, inductance is given in henries, and time is given in seconds). Restart.
If we take this to the limit of ƒ → 0 (DC circuits), then a capacitor is essentially an open circuit. At high frequencies, the capacitor is essentially a short circuit (acts like a wire with little or no resistance).
Exploration authored by Anne J. Cox.
Script authored by Wolfgang Christian and Anne J. Cox.
© 2004 by Prentice-Hall, Inc. A Pearson Company