Question Detail
Question
An electric spark is observed between two parallel plates 2.5 cm apart in air. If the potential across the plates is 60 kV just before the spark, determine the maximum electric field the air can support.
Correct Answer
Option A is the correct answer.
Detailed Explanation
E = V/d = (60,000 V)/(0.025 m) = 2.4x106 V/m. This is the 'dielectric strength' (breakdown field) of air - beyond it the air ionizes and a spark jumps.
Hint
E = V/d = (60,000 V)/(0.025 m) = 2.4x106 V/m.