A series RLC circuit has

PHYSICS · Subjective · CBSE · Physics · Alternating Current · Alternating Current

Problem

L = 50\,\text{mH}

C = 5\,\mu\text{F}

and

R = 20\,\Omega

. It is driven by an a.c. source of peak voltage

V_m = 10\,\text{V}

with variable frequency. (a) Calculate the resonant frequency

f_0

of the circuit. (b) Find the maximum current amplitude

I_{m,\text{max}}

at resonance. (c) On a set of qualitative axes, draw the expected variation of current amplitude

I_m

with frequency

f

for this circuit. Mark the point corresponding to

f_0

and

I_{m,\text{max}}

. (d) Using your sketch, describe what happens to the current amplitude when the driving frequency is (i) much lower than

f_0

and (ii) much higher than

f_0