Consider a parallel-plate capacitor connected to a constant voltage battery. If the plates are pulled apart to double their initial separation while the battery remains connected, how do the stored charge and electrostatic energy change?

💡 Solution & Explanation

When a capacitor remains connected to a constant voltage source, the electrical potential difference across its plates stays fixed. Doubling the plate separation halves the capacitance because capacitance is inversely proportional to plate distance. Since charge equals capacitance multiplied by voltage, the stored charge decreases by half. Similarly, the electrostatic energy stored, given by half the product of capacitance and voltage squared, also decreases by half. Plausible distractors confuse this scenario with a disconnected isolated capacitor where charge is conserved. Capacitors are fundamental energy-storing components in electronic tuning circuits.