Final answer:
The maximum potential difference between two parallel conducting plates is calculated by multiplying the maximum electric field strength that air can withstand, which is 3.0 × 10⁶ V/m, by the separation distance between the plates.
Step-by-step explanation:
The maximum potential difference that can be applied to the terminals a and b refers to the highest voltage that can be set between two parallel conducting plates before the air between them becomes conductive. For dry air, the breakdown strength is 3.0 × 10⁶ V/m, which is the maximum electric field strength that the air can withstand without leading to a discharge or spark.
To find the maximum potential difference, we use the equation V = E × d, where V is the potential difference, E is the electric field strength, and d is the separation distance between the plates.
For example, with a separation of 2.5 cm (or 0.025 m), the maximum potential difference would be
V = (3.0 × 10⁶ V/m) × 0.025 m = 75,000 V, also expressed as 7.5 × 10⁴ V.