An inductor, L=3mH, a resistor R=8 ohms and a capacitor C=10x10^-6 are connected in series with an AC source whose rms is 25V. find the resonance frequency, and frequencies at which the rms current is 50% of the value of resonance frequency?

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radar · Answer

The formula for resonant frequency is:

$$1\over2\pi \sqrt{LC}$$Giving a frequency around 918. Hz
inductive reactance XL=2pi F L=17 Ohms

Q=Xl/r=17/8=2

bandpass = 918/2=459
at 918 plus and minus 229 Hz the rms current will drop to 70.7% of the value at resonance at 918 Hz