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In a series LCR circuit, obtain the conditions under which (i) the impedance of the circuit is minimum , and (ii) wattless current flows in the circuit. |
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Answer» Solution :Impedance of series LCR circuit is given by `Z = sqrt(R^(2) + (X_(L) - X_(C))^(2)` or for Z to be minimum, `X_(L) = X_(C)` (or `omega = (1)/(sqrt(LC))`) For WATTLESS CURRENT to flow CIRCUITS should not have any ohmic resistance i.e., R = 0 Alternatively : Power `= V_(rms)I_(rms) cos phi` for `phi = 90^(@) = pi//2` Power = 0 `:.` Wattless current flows when the impedance of the circuit is purely inductive / capacitive of the combination of the two. |
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