LC oscillation
Electric and magnetic energy slosh back and forth between capacitor and coil.
A charged capacitor discharges through a coil: the capacitor's electric field energy gradually turns into the coil's magnetic field energy, and when the current is at its maximum the charge on the capacitor is zero. The coil's self-inductance then charges the capacitor in the opposite direction. Electric and magnetic energy keep converting into each other while the total energy stays constant. The larger the inductance or capacitance, the slower the oscillation.
Electric and magnetic energy
As one curve rises the other falls; at any instant their sum equals the total energy.
Think about it
If the capacitance is increased to 4 times its original value, how does the oscillation frequency change?
It halves. f = 1/(2π√(LC)); when the capacitance becomes 4 times as large, √(LC) becomes 2 times as large. Tuning a radio works by changing the capacitance to change the oscillation frequency.
Model assumptionsIdeal circuit, no resistive loss · Capacitor first charged to 10 V · Slowed down: one period takes about 3 s with default settings
Data log
Set the parameters and click “Record data”. Record several rows with different parameters to plot their relationship and fit a straight line; pause and record at different times to study how a reading changes with time.