81-2 Ohm's law Ohms law states that voltage across many types of conducting materials is directly proportional to the current flowing through the material. Ri or R R--resis tan ce(Q )(linear resistor) The resistor is a passive element that cannot deliver power or store energy. R P=U=UG=i/G P=D=2=2/R /G--conduc tance(s)/
§1-2 Ohm' s law Ohm' s law states that voltage across many types of conducting materials is directly proportional to the current flowing through the material. i 0 = Ri The resistor is a passive element that cannot deliver power or store energy. [G conduc tance( S )] p i G i / G − − = = = 2 2 i G + − + − R p i Ri / R 2 2 = = = i R − −resistance( )( linear resistor ) i or R =
The current through and voltage across a resistor must both vary with time in the same manner If: R=10,D(t=2sin 100tv we have i=u/R=0.2 sin 100tA and p=vi=0.4(sin 100t)w We define a short circuit as a resistance of zero ohms We define a open circuit as an infinite resistance
The current through and voltage across a resistor must both vary with time in the same manner. p i p t 0 T We define a "short circuit" as a resistance of zero ohms. We define a "open circuit" as an infinite resistance. If : R = 10,(t) = 2sin100t V and p i t W i R t A we have 2 0.4(sin100 ) / 0.2sin100 = = = =