This applet shows a simple circuit involving an inductor, which is a device that resists changes in current flow. When the simulator starts up, there is 5V across the inductor, and no current. Over time, the voltage across the inductor decreases, allowing the flow of current to slowly increase until it acts as a closed circuit; current flows freely across it.
Click on the switch to "discharge" the inductor (connecting a resistor across its terminals, which causes the current to go to zero), and then click on it again to reconnect it to the supply voltage.
The scope below the circuit shows the voltage across the inductor in green, and the current in yellow.
Next: RLC Circuit