Question

which of the following is true regarding current in an external circuit? a) the flow of an alternating current switches direction when a generators terminals change its charge.

Explanation:

First, analyze option A: Alternating current (AC) naturally changes direction periodically due to the generator's magnetic field interaction, not because terminals change charge. But since this is the only option shown (assuming others might be missing, but based on AC properties, the description here has a slight wording issue but the core idea of AC changing direction is related to generator operation. Wait, actually, the standard reason for AC direction change is the rotation of the generator's coil in the magnetic field, causing the induced emf to reverse, hence current reverses. However, among the given (only A here, maybe a partial question), but if we consider the option: AC current does switch direction, and in a generator, the terminals' "charge" change (actually potential difference reversal) causes it. So if this is the only option, we evaluate it. The key is that AC changes direction periodically, which is due to the generator's operation (like the coil rotating, leading to terminal voltage reversal, hence current direction change). So option A's statement, while wording might be simplified, is the true one (assuming other options are false, but since only A is shown, we conclude A is correct as AC does switch direction in external circuit due to generator's terminal voltage reversal (charge - related in a sense, as voltage is charge difference)).

Answer:

A. The flow of an alternating current switches direction when a generator's terminals change its charge.