ch31-p057 - 57. (a) The power factor is cos , where is the...

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57. (a) The power factor is cos φ , where is the phase constant defined by the expression i = I sin( ω t ). Thus, = – 42.0° and cos = cos(– 42.0°) = 0.743. (b) Since < 0, t > t . The current leads the emf. (c) The phase constant is related to the reactance difference by tan = ( X L – X C )/ R . We have tan = tan(– 42.0°) = –0.900, a negative number. Therefore, X L – X C is negative, which leads to X C > X L . The circuit in the box is predominantly capacitive. (d) If the circuit were in resonance X L would be the same as X C , tan would be zero, and would be zero. Since is not zero, we conclude the circuit is not in resonance. (e) Since tan
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This note was uploaded on 06/03/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.

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