Question

An RLC circuit has a sinusoidal voltage supplied to it at 316 kHz with a peak voltage of 505 V; a 35 k? resistance; a 13 ?F capacitance; and a 45 H inductance. What is the peak current for this circuit?

An  circuit has a sinusoidal voltage supplied to it at 316  with a peak voltage of 505 ; a 35  resistance; a 13  capacitance; and a 45  inductance. What is the peak current for this circuit?

11 ?A

5.4 ?A

14 ?A

5.7 ?A

Answer 1

Last option 5.7 ?A is the correct answer.

Explanation -

Determine the value of inductive and capacitive reactances -

X(L) = 2?fL = ( 2? * 316000 * 45) = 8.93 * 10^7 ohms

X(C) = 1 / (2?fC) = 1 / (2? * 316000 * 13 * 10^-6) = 0.039 ohms

R = 35k?

Now look at the above values, the resistance and the capacitive reactance are negligible compared to the 89.3 M? reactance of the inductor.

Forget them.

You are given the peak voltage, so when you plug the values into Ohm's Law, you are going to get peak current anyway. There's no "root 2" involved.

Therefore, peak current of the circuit = Imax = V / XL = 505 V / 89.3 M? = 5.66 ?A = 5.7 ?A