Experiment 19 - The Internal Resistance of the Capacitor
The internal resistance of a battery limits the current in case of a short circuit.
However, there are situations where you want a very large current.
In that case you need to take a look at capacitors...
Capacitors have a very low internal resistance.
You can illustrate this with the circuit shown...
Circuit internal resistance of a capacitor.
Circuit diagram internal resistance of a capacitor.
Capacitors are used wherever you need very short high current pulses,
eg in spot welding
or in the generation of high magnetic fields.
View circuit internal resistance of a capacitor. (Enlarge)
By pressing the pushbutton switch S1 you charge the two
capacitors C1 and C2.
In a second step, you bring the two tips of the loose wires in contact.
This shorts the capacitors
and you watch two things...
a small flash at the moment of short circuit,
whereupon the two tips "stick" together....
The high short-circuit current welded the tips together...
You can never obtain the same result with a 9 Volt Block Battery.
The higher internal resistance prevents this.