September 23, 2010University Physics, Chapter252Direct CurrentWe will study charges in motionElectric charge moving coherently from one region to another is called electric currentCurrent is flowing through light bulbs, iPods, and lightning strikesCurrent usually consists of mobile electrons traveling in conducting materialsDirect current is defined as a current that flows only in one direction in the conductorMost of our electric technology is based on Alternating Current –Chapter 26Computers, electronic devices are based on direct currents.
September 23, 2010University Physics, Chapter253Electric Current (1)We define the electric currentias the net charge passing a given point in a given timeRandom motion of electrons in conductors, or the flows of electrically neutral atoms, are not electric currents in spite of the fact that large amounts of charge are moving past a given pointIf net charge dqpasses a point in time dtwe define the current ito bedqidt
This preview has intentionally blurred sections.
Sign up to view the full version.
September 23, 2010University Physics, Chapter254Electric Current (2)The amount of charge qpassing a given point in time tis the integral of the current with respect to time given byCharge conservationimplies that charge flowing in a conductor is never lostTherefore the same amount of charge must flow into one end of the conductor and exit from the other end of the conductor0tqdqidt