Question

An uncharged capacitor and a resistor are connected in series with a switch and a 12 V battery. At the instant the switch is closed, the voltage across the resistor is

Answer 1

Answer:

V = 12 V

Explanation:

• Since a capacitor can't change the voltage between its plates  instantaneously, this means that just after the switch is closed, the voltage through the capacitor is zero.
• So, the current that flows in this moment is the same that would flow in a series circuit with only one resistor connected to the battery.
• Applying KVL to the circuit (neglecting the presence of the capacitor which can be replaced by a short circuit just after closing the switch), the voltage through the resistor must be equal to the one of the battery, i.e., 12 V.