A biomedical instrument is driven from a source of rms through a series circuit…
PHYSICS · Multi-part · CBSE · Physics · Alternating Current · Alternating Current
Problem
A biomedical instrument is driven from a 5.0kHz source of 20V rms through a series circuit consisting of a resistor R=60Ω, a fixed inductor L=10mH, and a variable capacitor C.
(i) Derive an expression for the impedance Z(C) of the circuit as a function of the capacitance at the operating frequency.
(ii) Show analytically that Z(C) attains its minimum value when the circuit is in resonance.
(iii) Calculate the capacitance that minimises the impedance at 5.0kHz and find the corresponding rms current.
(iv) Determine the phase angle between the current and the supply voltage at this condition and state its significance for power transfer.