Final answer:
The current from a rotating loop with slip rings is alternating current because the loop is continuously changing its position with respect to the magnetic field, resulting in a continuously changing magnetic flux through the loop.
Step-by-step explanation:
The current from a rotating loop with slip rings is alternating current. This is because the loop is continuously changing its position with respect to the magnetic field, resulting in a continuously changing magnetic flux through the loop. As a result, an alternating current is induced in the loop. The direction of the current changes periodically as the loop rotates.