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As the frequency of an ac circuit increases, the current first increases and then decreases. What combination of circuit elements is most likely to comprise the circuit ? |
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Answer» Inductor and capacitor. `X_L=2pivL "" therefore X_L prop v` where v is frequency of the AC circuit, reactance of the capacitor `X_C=1/(2pivC)` `therefore X_C prop 1/v` On increasing frequency v CLEARLY `X_L` increases and `X_C` decreases. For L-C-R circuit `Z=SQRT(R^2+(X_L-X_C)^2)` where Z=impedence of the circuit `=sqrt(R^2+(2pivL-1/(2pivC)^2)` As frequency (v) increases, Z decreases and a certain value of the frequency known as resonant frequency `v_0` impedence Z is minimum that is `Z_"min" = R`, current varies inversely with impedence and at `Z_"min"` current is MAXIMUM. 
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