<java_applet

 code=Circuit
 height="500" width="500" 
 archive="Circuit.jar" 
 p1name="pause" p1value=20 
 p2name="startCircuit" p2value="Induct_Example.txt" 
 p3name="startLabel"  p3value="RL Example" 
 p4name="useFrame" p4value="false"

/>

Notice how when the switch is applied, the voltage and current lag. The inductor can be thought of as a component that resists change in current. The larger the inductance (units in Henry) the more it resists the change in current. So if a voltage were to be applied in an instance, the current will slowly (speed based on inductance value) climb or fall to the current that would be there if the inductor were replaced with a wire. The voltage will also lag because voltage is a function of current.

Notice when the switch is turned off that current still runs in the second circuit where there is only a resistor and inductor, but only for a short amount of time. This is because inductors store energy in a magnetic field, once the source of current is taken away and the inductor is applied to say a resistor in this case, the stored magnetic energy is translated to current that runs through the resistor. Since the energy stored in the magnetic field is small the current is quickly used up by the resistor and settles to 0volts and 0amps.

More details: http://en.wikipedia.org/wiki/Inductor http://en.wikipedia.org/wiki/Inductor