Math Problem Statement

Given the above circuit with voltage source and components as shown below, find the current: Vs = 800<-25, Vr = 30, L = 0.12H, C = 60uF

Given the above circuit with voltage source and components as shown below, find the current: Vs = 800<-25, Vr = 30, L = 0.12H, C = 60uF

Solution

The given circuit is an RLC series circuit powered by an AC voltage source Vs(t)=80025V_s(t) = 800 \angle -25^\circ volts, where we have a resistor RR, an inductor LL, and a capacitor CC in series.

Here’s how we can analyze the circuit to find the current:

Step 1: Convert the Voltage Source to Phasor Form

The voltage source is already given in phasor form: Vs=80025 volts.V_s = 800 \angle -25^\circ \text{ volts}.

Step 2: Impedance Calculation

We need to calculate the impedances of the resistor, inductor, and capacitor at a given frequency ω\omega.

  1. Resistor Impedance: The impedance of a resistor is purely real and is simply RR. ZR=R.Z_R = R. From the image, the value of RR isn't explicitly given, but vR=30v_R = 30 V suggests we will need this information to find the current.

  2. Inductor Impedance: The impedance of an inductor is given by: ZL=jωL.Z_L = j \omega L. Where ω\omega is the angular frequency of the source (we will need the source frequency for further calculation).

  3. Capacitor Impedance: The impedance of a capacitor is given by: ZC=1jωC.Z_C = \frac{1}{j \omega C}. Again, this depends on the angular frequency ω\omega.

Step 3: Total Impedance of the Circuit

The total impedance ZtotalZ_{\text{total}} is the sum of the impedances of the resistor, inductor, and capacitor: Ztotal=ZR+ZL+ZC=R+jωL+1jωC.Z_{\text{total}} = Z_R + Z_L + Z_C = R + j \omega L + \frac{1}{j \omega C}.

Step 4: Finding the Current

Once we have the total impedance, the current in the circuit can be calculated using Ohm's Law in phasor form: Is=VsZtotal.I_s = \frac{V_s}{Z_{\text{total}}}.

To complete the calculation, we would need either the frequency ff or the angular frequency ω\omega of the source. Could you provide the frequency or clarify the value of RR?

Here are five related questions you might consider:

  1. What is the angular frequency or the frequency of the voltage source Vs(t)V_s(t)?
  2. Is the value of the resistor RR given elsewhere in the problem or in other parts of the circuit?
  3. Should we assume a standard frequency (like 60 Hz or 50 Hz) for the AC source?
  4. Would you like a step-by-step explanation of how to derive the impedance of inductors and capacitors in AC circuits?
  5. How do phase angles affect current calculations in an RLC circuit?

Tip: When solving AC circuits, always make sure to work in phasor form for both voltage and current, as this simplifies the handling of sinusoidal sources.

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Math Problem Analysis

Mathematical Concepts

AC Circuit Analysis
Phasors
Impedance in RLC Circuits
Ohm's Law

Formulas

V_s = 800 ∠ -25°
Z_R = R
Z_L = jωL
Z_C = 1 / (jωC)
Z_total = Z_R + Z_L + Z_C
I_s = V_s / Z_total

Theorems

Ohm's Law
Phasor Analysis
Impedance Calculation in AC Circuits

Suitable Grade Level

Undergraduate - Electrical Engineering