Question

Why do capacitors oppose the change in voltage?

Answer 1

Why capacitors oppose the change in voltage:

1. Capacitors withstand voltage fluctuations because their voltage varies slowly.
2. The voltage varies slowly because the derivative is not finite if the voltage changes from one value to another quickly (i.e. discontinuously). This means that an infinite current would be necessary to adjust the voltage quickly.
3. Because an infinite current is not physically possible, the voltage cannot change instantly.
4. The time is determined by the size of the capacitor. A bigger capacitor will require more time to discharge/charge than a smaller one.
5. The statement that capacitors withstand voltage fluctuations is relative and time-dependent.
6. Capacitor charging and discharging is important because the capacity to regulate and anticipate the rate at which a capacitor charges and discharges is what makes capacitors useful in electronic timing circuits.
7. It occurs when a voltage is put across a capacitor and the potential cannot instantly increase to the applied value. As the charge on the terminals accumulates to its ultimate amount, it tends to reject the buildup of more charge.

Example:

1. For example, if you add a voltage to a resistor with a battery, it will instantaneously have that voltage across it.
2. When you remove the battery, the resistance immediately goes to 0 volts.
3. A capacitor, on the other hand, requires both time to charge and time to discharge.
4. So, say you connect a capacitor to a $5\mathrm{V}$ battery and inquire what the voltage across the capacitor is at that moment.
5. Thus, capacitors resist instantaneous voltage fluctuations.