If the dielectric constant and dielectric strength be denoted by k and x respectively, then good capacitor must have:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → high k and high x
The dielectric constant k decides how much a dielectric raises the capacitance (\( C = kC_0 \)), so a high k lets the capacitor hold more charge at the same potential difference. The dielectric strength x is the largest electric field the dielectric can bear before it breaks down and starts conducting, so a high x lets the capacitor work at a high voltage without leaking charge. A good capacitor needs both.
NCERT (2026-27):
Capacitors and Capacitance – “… The maximum electric field that a dielectric medium can withstand without break-down (of its insulating property) is called its dielectric strength; … Thus, for a capacitor to store a large amount of charge without leaking, its capacitance should be high enough so that the potential difference and hence the electric field do not exceed the break-down limits.”
Effect of Dielectric on Capacitance – “… Thus, the dielectric constant of a substance is the factor (>1) by which the capacitance increases from its vacuum value, when the dielectric is inserted fully between the plates of a capacitor.”