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S E C T I O N 3 2 . 5 • Oscillations in an LC Circuit 1017 We can solve for Q by noting that this expression is of the same form as the analogous where k is the spring constant, m is the mass of the block, and The solution of this equation has the general form (Eq. 15.6), x " A cos(1t , 2) 1 " √ k/m
. d 2 x dt 2 " # k m x " #1 2 x m m m m Q = 0 I = 0 t = 0 t = T 2 +Q max –Q max E C L C L Q = 0 I =I max I = 0 –Q max +Q max B C L t = T 4 C L I =I max t = 3 4 T I = 0 +Q max –Q max E C t =T L (a) k x = 0 x = 0 v = 0 A (b) x = 0 v max (c) x = 0 v = 0 A (e) x = 0 m v = 0 A x = 0 (d) x = 0 v max – – – – + + + + – – – – – – – – B + + + + + + + + S E Active Figure 32.17 Energy transfer in a resistanceless, nonradiating LC circuit. The capacitor has a charge Q max at t " 0, the instant at which the switch is closed. The mechanical analog of this circuit is a block–spring system. At the Active Figures link at http://www.pse6.com, you can adjust the values of C and L to see the effect on the oscillating current. The block on the spring oscillates in a mechanical analog of the electrical oscillations. A graphical display as in Figure 32.18 is available, as is an energy bar graph. |