57. (a) The power factor is cos φ, where is the phase constant defined by the expression i = Isin(ωt– ). 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 = (XL– XC)/R. We have tan = tan(– 42.0°) = –0.900, a negative number. Therefore, XL– XCis negative, which leads to XC> XL. The circuit in the box is predominantly capacitive. (d) If the circuit were in resonance XLwould be the same as XC, tan would be zero, and would be zero. Since is not zero, we conclude the circuit is not in resonance. (e) Since tan
This is the end of the preview. Sign up
access the rest of the document.
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.