A DC generator converts mechanical energy into DC electrical energy. The basic construction of the DC generator is similar to that of the simple alternator, except that the two slip rings are replaced with a single split ring. As the conducting loop rotates in a uniform magnetic field, the magnetic flux through the loop changes sinusoidally, resulting in induced emf. Here the split ring acts as a commutator. The commutator switches the contacts for each half rotation of the loop, ensuring the same polarity for the induced emf. Similar to an alternator, the induced emf is zero when the magnetic flux is either maximum or minimum. But because of the commutator, the induced emf is never negative and has a maximum when the magnetic flux is zero. The magnitude of the average induced emf is estimated by replacing the sinusoidal term from the simple alternator with its average value. The magnitude of the induced emf is proportional to the angular velocity for the given magnetic field and the area of the loop.