Direct vs. Alternating Current

• Direct current:• Current constantly flows in same direction

• Alternating current:• Current switches direction back & forth

The War of the Currents

• Team Edison• Used D.C. as primary means of electrical power

• Team Tesla• Used A.C. as primary means of electrical power

Photograph of Thomas Edision by Louis Bachrach, Bachrach Studios, restored by Michel Vuijlsteke; Photograph of Nikola Tesla by Napoleon Sarony

The War of the Currents

Video obtained from: https://www.youtube.com/watch?v=xyQfrzBfnDU

D.C. and A.C. Motors

• Motors are the machines behind the electrical age• Stator: stationary part of motor• Rotor: rotating part of motor• Commutator (DC only): allows current to constantly flow in one

direction on one side of motor• Magnet: provides constant B field• Keep stationary (D.C.) or spin it (A.C.)

• Electromagnet: can provide constant or changing B field• Keep on (D.C.) or cycle it on & off (A.C.)

D.C. Motor

Video obtained from: https://www.youtube.com/watch?v=LAtPHANEfQo

A.C. Motor

Video obtained from: https://www.youtube.com/watch?v=LtJoJBUSe28

A.C. Motor (Single-Phase Induction)

Video obtained from: https://www.youtube.com/watch?v=awrUxv7B-a8