Electronic – Voltage supply plus ideal current source connected to capacitor in series

capacitor

This might be a wierd question but I was asked this in an interview. I know the basic behaviour of an RC network when it is connected to a battery (practical situation) and also the ideal situation when there is an ideal constant current source in series charging a capacitor (when the circuit is like a loop). However, what will happen if there is both an ideal current source along with a voltage supply in series with the capacitor. Edit: Added a picture, need to sketch the capacitor voltage at node A.enter image description here

Best Answer

However, what will happen if there is both an ideal current source along with a voltage supply \$\color{red}{\boxed{\text{in series}}}\$ with the capacitor.

A voltage source that is \$\color{red}{\boxed{\text{in series}}}\$ with a current source is relegated to obscurity. You might just as well remove the voltage source and replace it with a short-circuit. The current source wins every time and defines the current flow.

On the other hand, a voltage source in parallel with a current source is different - the voltage source wins and defines the voltage; the current source is of no-consequence and can be replaced by an open-circuit i.e. removed.