A DC generator creates a current that ? and an AC generator creates a current that ? .

A DC generator creates a current that ? and an AC generator creates a current that ? .

• A. Flows in 2 directions / flows in 1 direction
• B. Flows in 1 direction / flows in 2 directions
• C. Flows north to south / flows south to north
• D. Flows south to north / flows north to south

Answer: (B)

The key idea is unidirectional versus alternating current. A DC generator is designed so that the current in the external circuit flows in one direction. This happens because a commutator reverses the connection to the load as the coil rotates, so the induced emf that would naturally reverse polarity ends up driving current in the same direction continuously. In contrast, an AC generator produces an emf whose polarity reverses as the rotor turns, and there’s no mechanism to keep the external circuit connected to a single polarity. As a result, the current in the external circuit alternates, flowing first in one direction and then in the opposite direction during the next half cycle. Over a full cycle, it has flowed in both directions.

The key idea is unidirectional versus alternating current. A DC generator is designed so that the current in the external circuit flows in one direction. This happens because a commutator reverses the connection to the load as the coil rotates, so the induced emf that would naturally reverse polarity ends up driving current in the same direction continuously. In contrast, an AC generator produces an emf whose polarity reverses as the rotor turns, and there’s no mechanism to keep the external circuit connected to a single polarity. As a result, the current in the external circuit alternates, flowing first in one direction and then in the opposite direction during the next half cycle. Over a full cycle, it has flowed in both directions.