Physics 2001 JAMB Past Questions - Question 45: At resonance, the pnase angle in an a.c. circuit is

Correct Answer

C

Explanation

Cos0 =R/z ;At resonance R=z0 =cos-1(1) =0At resonance in an AC circuit, the phase angle between the current and voltage is 0 degrees (or sometimes expressed as 360 degrees). This means that the current is in phase with the voltage, and the circuit is purely resistive at this point.

Resonance occurs in circuits containing reactive components like inductors and capacitors when the impedance of these components cancels each other out, and the net impedance becomes purely resistive. At this point, the capacitive reactance and inductive reactance become equal in magnitude but opposite in phase, resulting in a net impedance of zero, which is purely resistive.

In a series RLC circuit (containing a resistor, inductor, and capacitor in series), the phase angle is 0 degrees at resonance, indicating that the current is in phase with the voltage. This is because the voltage drop across the resistor and the voltage drop across the inductor and capacitor cancel each other out in terms of phase, leading to a net phase angle of 0 degrees.