<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (October 2016) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (October 2016) (Learn how and when to remove this template message) </Td> </Tr> <P> A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft . Typical applications include electric motors, alternators and electric generators . </P> <P> For certain types of electric motors or generators to function, the coils of the rotor must be connected to complete an electrical circuit . Originally this was accomplished by affixing a copper or brass commutator or' slip ring to the shaft, with springs pressing braided copper wire' brushes' onto the rings which conduct the current . Such brushes provided poor commutation as they moved from one commutator segment to the next . The cure was the introduction of' high resistance brushes' made from graphite (sometimes with added copper). Although the resistance was of the order of tens of milliohms, they were high resistance enough to provide a gradual shift of current from one commutator segment to the next . The term brush remains in use . Since the brushes wear out, they can be replaced in products intended to allow maintenance . </P>

Explain the function of the brush ring in electric generator