Unformatted text preview: m r R 2 + ± ω d L1 ω d C ² 2 (48) We can also ﬁnd the overall phase shift between the current and the potential using the standard methods of vector analysis. tan φ = X LX C R If we plot this current amplitude versus the natural frequency, we see the phenomena of resonance emerge (see ﬁgure 35). By looking at the plot we can clearly see that the largest amplitude of the current is induced when the circuit is driven precisely at its resonance frequency. ω d = ω = 1 √ LC Figure 35: Resonance in an RLC circuit. 12.5 Problems Problem 31.21 In an oscillating LC circuit, L = 3 mH and C = 2 . 7 μF . At t = 0 the charge on the capacitor is zero and the current is 2 A . (a) What is the maximum charge that will appear on the capacitor? (b) At what earliest time t > 0 is the rate at which energy is stored in the capacitor greatest, and (c) what is that greatest rate? 49...
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 Spring '08
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 Physics, RC circuit, LC circuit, ﬁnal current amplitude

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