Question

Here you have a battery, a light bulb and a capacitor. If the capacitor is pretty big, what you will notice is that, when you connect the battery, the light bulb will light up as current flows from the battery to the capacitor to charge it up. The bulb will get progressively dimmer and finally go out once the capacitor reaches its capacity.

the statement above is from www.howstuffworks.com, why does the light bulb goes out once the capacitor is fully charged? Does this mean capacitor don't conduct electricity when its capacity full?

Answer 1

thats right. when the capacitor is fully charged there is no electric potential between each of its terminals and the battrey's one. so there is no charge transfering and no current. that's to say when the capacitor is fully charged it has an infinite resistant.

Answer 2

https://www.youtube.com/watch?v=IvFVu7Jxa2I&feature=fvwrel
Tat is a video about how capacitor get charged, I don't understand how the negative charges transfer to the other side when it is fully charged. And why the electron flow getting slower when it is approaching its maximum capacity, is it because the repulsive force between the moving electron and the electrons in the capacitor getting smaller when less electrons remain inthere.

Answer 3

Does we have to reverse the connection of the capacitor to deplete the charge in it?

Answer 4

the reason that both plates would be charged is the induction. an amount of charge equal to the charge on the first plate will be induced on the other plate. cause the electrons which are flocked into the first plate repulse the electrons from other plate.

and the reason that charges transfer to the capacitor's plate is the difference in its potential and the battery's terminal (which is connected to the plate). the more the charge transfers to the plate the less the electric potential (difference) would be. so the current would be less. your conclusion is also right. the more the charge gets to the capacitor the larger the repulsive force exerts on coming electrons.

since plates have the same charge (but opposite in sign) its enough to make a connection between them to deplete the charge.

Answer 5

just to confirm my understanding.


The capacitor become insulator because of its positive and negative charge get attracted to the corresponding terminal and left no charge carrier in them then cut the circuit.


And in this circuit, the capacitor only release its charge when the ac current oscillate to 0 current, then the polarized charge flow around the circuit?