In the Capacitors section of All About Circuits (Vol. 1 DC), it says:
"A capacitor's ability to store energy as a function of voltage (potential difference between the two leads) results in a tendency to try to maintain voltage at a constant level. In other words, capacitors tend to resist changes in voltage drop. When voltage across a capacitor is increased or decreased, the capacitor "resists" the change by drawing current from or supplying current to the source of the voltage change, in opposition to the change."
I find this statement to be the opposite of what I thought a capacitor was supposed to do. I thought that if you connected a capacitor to a voltage source, the voltage source would induce a current and a voltage across the capacitor would appear. I don't see how a capacitor could be able to charge and dissipate energy (thereby changing its voltage) and yet still "resist" any change in voltage. I thought a change in voltage was the whole point!
My other question about capacitors is why, if it was connected to a voltage source in a single-loop circuit, the maximum voltage across it is the same as the voltage source. I understand that if it were a resistor, not a capacitor, then there is a maximum voltage, but since a capacitor is designed to accumulate charge on each of it's plates, why does the voltage source dictate how much charge it can accumulate? What if the plates are very large and are capable of storing more charge and thus having a larger voltage drop across it than the voltage source has?
I feel like I'm missing something BIG here! Thanks for your help.
"A capacitor's ability to store energy as a function of voltage (potential difference between the two leads) results in a tendency to try to maintain voltage at a constant level. In other words, capacitors tend to resist changes in voltage drop. When voltage across a capacitor is increased or decreased, the capacitor "resists" the change by drawing current from or supplying current to the source of the voltage change, in opposition to the change."
I find this statement to be the opposite of what I thought a capacitor was supposed to do. I thought that if you connected a capacitor to a voltage source, the voltage source would induce a current and a voltage across the capacitor would appear. I don't see how a capacitor could be able to charge and dissipate energy (thereby changing its voltage) and yet still "resist" any change in voltage. I thought a change in voltage was the whole point!
My other question about capacitors is why, if it was connected to a voltage source in a single-loop circuit, the maximum voltage across it is the same as the voltage source. I understand that if it were a resistor, not a capacitor, then there is a maximum voltage, but since a capacitor is designed to accumulate charge on each of it's plates, why does the voltage source dictate how much charge it can accumulate? What if the plates are very large and are capable of storing more charge and thus having a larger voltage drop across it than the voltage source has?
I feel like I'm missing something BIG here! Thanks for your help.