InterviewSolution
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InterviewSolution
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A coil of inductance 0.50H and resistanace `100 Omega` is connected to a 240V, 50Hz ac supply. What are the maximum current in the coil and the time lag between boltage maximum and current maximum? |
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Answer» Correct Answer - `1.82A; 3.2 xx10^(-3)s` Impedance of the coil: `Z=sqrt(R^(2)+(2 pi f l)^(2)) =sqrt(100^(2)+4 pi^(2) (50)^(2)(0.5)^(2))=186.2 Omega` Maximum current: `I_(0) =(E_0)/(Z) =(240 sqrt(2))/(186.2) = 1.82A` `tan phi - (X_(C )-X_(L))/(R ) =(0-2 pi (50)(0.5))/(100) = -(pi)/(2)` `implies phi = - tan^(-1) ((pi)/(2)) =-27.51^(@) =-1.003 rad ` Let emf be maximum at `(t_1)`, then `(omega t_(1))=(pi)/(2)` [ we have `E=E_(0) sin omega t and I=(I_0) sin (omega t + phi]` Let current be maximum at `(t_2)`, then` (omega t_(2))+phi =(pi)/(2)` form above we have `omega(t_(2)-t_(1)) =-phi` Time lag between voltage maximum and current maximum : `(t_2)-(t_1) =-(phi)/(omega) = (1.003)/(2 pi f ) =3.2 xx10^(-3)s`. |
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