An electric generator differs from an AC generator in its use of a split ring instead of two slip rings. The purpose of the split ring in a DC generator is to:

1. In an AC generator, two slip rings let the external current reverse each half rotation, giving AC. 2. For DC, the chapter describes fixing a split ring on the axle so that the upward-moving branch always touches one brush and the downward branch the other. 3. This keeps the external-circuit current flowing in one direction, which is why it is a DC generator. 4. The option describes the AC-generator behaviour with slip rings, the opposite of what the split ring achieves. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 4 "Effects of Electric Current", p.69_