Math Problem Statement

In figure Q2, vs1(t) = 5cos(2πft) V where f = 1kHz and Vs2 = 15 V. Determine i2(t).

Solution

To determine i2(t)i_2(t), let’s go through the solution in steps. We are dealing with an AC circuit containing both resistive and capacitive components.

Given Information

  1. vs1(t)=5cos(2πft)v_{s1}(t) = 5 \cos(2 \pi f t), where f=1kHzf = 1 \, \text{kHz}.
  2. Vs2=15VV_{s2} = 15 \, \text{V}.
  3. The capacitor value is 0.22μF0.22 \, \mu\text{F}.
  4. Resistors are 1kΩ1 \, \text{k}\Omega and 2kΩ2 \, \text{k}\Omega.

Step-by-Step Solution

  1. Convert Frequency to Angular Frequency: Since f=1kHz=1000Hzf = 1 \, \text{kHz} = 1000 \, \text{Hz}, ω=2πf=2π×1000=2000πrad/s.\omega = 2 \pi f = 2 \pi \times 1000 = 2000 \pi \, \text{rad/s}.

  2. Impedance of the Capacitor: For a capacitor, the impedance ZCZ_C is given by: ZC=1jωC.Z_C = \frac{1}{j \omega C}. Substituting the values of ω\omega and C=0.22μF=0.22×106FC = 0.22 \, \mu\text{F} = 0.22 \times 10^{-6} \, \text{F}: ZC=1j2000π0.22×106.Z_C = \frac{1}{j \cdot 2000 \pi \cdot 0.22 \times 10^{-6}}. Calculating this gives: ZCj723.4Ω.Z_C \approx -j723.4 \, \Omega.

  3. Total Impedance Seen by vs1(t)v_{s1}(t): The total impedance ZtotalZ_{total} from vs1(t)v_{s1}(t) to ground includes ZCZ_C, the 1kΩ1 \, \text{k}\Omega resistor, and the parallel combination of 2kΩ2 \, \text{k}\Omega and Vs2V_{s2}:

    • Combine the capacitor’s impedance ZCZ_C with the 1kΩ1 \, \text{k}\Omega resistor in series.
    • Then calculate the current divider for the 2kΩ2 \, \text{k}\Omega resistor.
  4. Calculate i2(t)i_2(t): Use Ohm’s law and AC analysis techniques to find i2(t)i_2(t).

Would you like a more detailed walkthrough of each step or additional clarifications?


Related Questions

  1. How would the solution change if the capacitor value were different?
  2. What if the frequency ff was increased to 10 kHz? How would i2(t)i_2(t) be affected?
  3. How can we analyze this circuit in the frequency domain?
  4. How would the response change if we replaced the AC source with a DC source?
  5. How does the current i2(t)i_2(t) vary with changes in Vs2V_{s2}?

Tip

In AC circuits, always convert all elements to their impedance form for easier analysis, especially when working with complex circuits involving capacitors and inductors.

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Math Problem Analysis

Mathematical Concepts

AC Circuit Analysis
Complex Impedance
Current Division

Formulas

Angular frequency: ω = 2πf
Capacitive impedance: Z_C = 1 / (jωC)
Ohm’s law for AC: V = IZ
Current divider rule

Theorems

Ohm's Law
Impedance of Capacitors in AC Circuits

Suitable Grade Level

Undergraduate Electrical Engineering