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Unformatted text preview: oiR = L di/dt + q/c o L di/dt + q/c + iR = 0 o L d 2 q/dt 2 + q/c + R dq/dt = 0 • Solution? o q = QeRt/2L cos ( ϖ l t + δ ) Charge on a capacitor o ϖ l = ( ϖ 2 (R/2L) 2 ) 1/2 where ϖ = (1/ LC) 1/2 o U = Q 2 /2C eRt/L AC Circuits • We learned that by rotating a coil in a magnetic field, a sinusoidal emf can be generated. What if such a generator (instead of a battery) is placed in a circuit? • Resistive load • ξ = ξ max sin ϖ t = v R o Let's assume that instantaneously the current i R is clockwise, i R = v R / R o By the loop rule, ξ v R = 0, therefore v R =V R sin ϖ t = ξ max sin ϖ t and i R = I R sin ϖ t = (v R / R) sin ϖ t o v R and i R are said to be phase, T = one period o Phasor Diagram • i R = I R sin ϖ t and v R =V R sin ϖ t ( or the projection of the phasors on y axis)...
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 Spring '07
 MAHLON,GREGORYDA
 Physics, Magnetism, Electrical resistance

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