Plzz me which best compares a brush and a commutator in an electric motor? a) both rotate when the motor is on. b) both carry electrical current from a power source. c) both remain stationary when the motor is on. d) both have a permanent magnetic field.

A brush and commutator in an electric motor both of them carry electrical current from a power source.

Brush in electric motor  are made up of  carbon  which contains electrical current between the wires in rest and the ones in motion

And commutator gives current to the motor winding

Therefore, option B is correct that is both carry electrical current from power source.

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.

i don’t know what the answer is i wish i