Explain why you expect E to be greater than 12EF[Equation (9.45)].
Direct Currents We will now start to consider charges that are moving through a circuit, currents. 1 Direct Current Current usually consists of mobile electrons traveling in conducting materials Direct current (DC) is defined as a current that flows only in one direction in the conductor Computers, electronic devices are based on direct currents. Many of our electric technology is based on Alternating Current (AC) – Chapter 26 13 Electric Current (1) We define the electric current i the charge passing a given cross-section in unit time A A Current = positive charge that passed through A “to the right” plus negative charge that passed through A “to the left” per unit time. i = A(q n+ + + −q )n v )− − − 14 Direct Current We will study charges in motion Electric charge moving coherently from one region to another is called electric current. Do not need to move net charge to produce current, just relative motion of charges usually n + n − n + += n v − − electric wires are not charged! 13 Again, wires do not need to be charged to conduct current: