Question

How do capacitors affect current?

Answer 1

The link between a capacitor and voltage and current can be summarized as follows: the capacitance and the rate of rising or fall of the voltage determine how much current flows through a capacitor. A strong positive current will be produced through a capacitor if the voltage across the capacitor rises quickly.

1. Smaller current through capacitor results from a slower increase in voltage across it. No current will flow through a capacitor if the voltage across it is constant and unchanging.
2. The formula for estimating the current flowing through a capacitor is: $i=C\frac{dV}{dt}$, where $i=$Current, and $C=$Capacitance.
3. The $\frac{dV}{dt}$ component of that equation is a derivative of voltage over time, which is another way of saying "instantaneous rate," or "how quickly is voltage increasing or decreasing at this precise moment." The most important lesson to be learned from this equation is that if the voltage is constant, the derivative is zero, indicating that the current is likewise zero. Because of this, the current cannot pass through a capacitor that is maintaining a constant $DC$ voltage.