# How does the current remains constant in an ideal capacitor?

In a tutorial given here, it is explained that the current remains constant upon sweeping the potential in an ideal capacitor.

Can someone explain in a descriptive way (in terms of the role of electrons) how it happens?

When applying a positive potential, we are charging the capacitor (right?) Why the current remains constant during charging?

Constant current means a constant flow of electrons in the circuit (right?) Then, how is this flow kept constant?

• Maybe try the physics stack exchange site? – Andy aka Jul 2 '17 at 10:11

Can someone explain in a descriptive way

If you had a perfect undriven flywheel spinning at 1000 rpm and applied a constant loading torque to it, the speed would reduce linearly to zero over a period of time.

Imagine the flywheel is the capacitor, the speed is the voltage and the torque is the current.

If on the other hand you drove that flywheel from rest with a constant torque, the speed would rise linearly with time.

If you can understand intuitively how this happens with a flywheel then you have your answer because, apart from symbolic stuff in the formulas, the formulas are the same.

Can someone explain in a descriptive way (in terms of the role of electrons) how it happens?

Not really a good fit for this site - try SE.Physics.

Because we are using a linear voltage sweep, the current through the capacitor is constant when the voltage is increasing or decreasing.

In the article they are applying a linearly increasing voltage to the capacitor so the current will be constant as in the equation $I = C \frac{dV}{dt}$.

You may be confusing it with the standard RC charge / discharge curves which give an exponential curve due to the decreasing current as the potential difference across the resistor decreases.