MHT CET202525 Apr 2025Evening ShiftPhysicsAlternating CurrentActual
An a.c. source of frequency ' f ' is connected to a circuit containing an inductance ' L ' and resistance ' R ' in series. The impedance of this circuit is
Options
- AR ^2+2 fL ^2
- BR^2+L^2
- CR +2 fL
- DR^2+4 ^2 f^2 L^2
Correct answer
D. R^2+4 ^2 f^2 L^2
Step-by-step solution
Inductive reactance X_L depends on angular frequency and inductance L , with X_L = L . Given = 2 f , it follows that X_L = 2 f L . In a series RL circuit, the impedance Z is the phasor sum of resistance R and inductive reactance X_L , yielding Z = R^2 + X_L^2 . Substituting for X_L provides Z = R^2 + (2 f L)^2 = R^2 + 4 ^2 f^2 L^2 . The derived expression corresponds to option D .