18-6 Electric Power P=Power=energy transformed/time=QV/t P=IV=I(IR)=I2R=(V/R)V=V2 /R See Example 18-7 p 539 See Example 18-8 p539 See Example 18-9 p539
18-7 Power in Household Circuits • Amperage is added in a series of household products. • Power is carried in a low amperage and high voltage because of the I2 R =IV paradox. • Voltage is constant for each appliance, but amps are summed. • See Example 18-10 p541
18-8 AC current • So far we have talked about batteries, which produce a steady flow, like a river… • AC current produces current that moves forward and then back again like the waves at a shoreline. See page 542 • AC current can be produced by an AC generator so that it has a –I and +I in a sine-wave form.
AC cont’d • I=V/R=(Vo /R)(sin2pft)=Iosin2pft • P=I2 R= I2osin22pft • Rms means root mean square…they are not really averages, but are the effective values. • Irms = See pg 543 • See example 18-11 and 18-12 p543 and 544.
HOMEWORK • P552 23-29, 33-37,40-44 , 47,51-52 DUE BOP Monday. • Test Tuesday chapter 18. • Packets due WEDNESDAY!!!!