Test: Network Theorems (A.C.) - 1 - Electronics and Communication Engineering (ECE) MCQ

To calculate the power delivered to the speaker in the given circuit, we need to consider the voltage across the speaker and the current passing through it. Let's break down the solution into the following steps:

Step 1: Determine the Voltage across the Speaker
- The voltage across the speaker can be calculated using Ohm's Law: V = I * R
- Given that VS = 4.5 VRMS and the impedance of the speaker is 8 Ω, we can calculate the voltage across the speaker as follows:
- VS = IR
- I = VS / R
- I = 4.5 / 8
- I = 0.5625 A

Step 2: Calculate the Power delivered to the Speaker
- The power delivered to the speaker can be calculated using the formula: P = V * I
- Substituting the values we calculated earlier:
- P = 4.5 * 0.5625
- P = 2.53125 W
- Converting the power to milliwatts: 2.53125 * 1000 = 2531.25 mW

Therefore, the power delivered to the speaker at the determined frequency when VS = 4.5 VRMS is 2531.25 mW, which is closest to option D: 424 mW.

Correct option is B

The resultant of the currents flowing in the same direction in a particular branch must be equal to the sum of the individual currents.

For example, 3A and 5A are the currents flowing in the same direction in a branch.

Resultant current flowing though the branch I_total​=3+5=8A

Thus option B is correct.

In Superposition theorem, while considering a source, all other current sources are open circuited. Superposition theorem is not valid for power responses. It is applicable only for computing voltage and current responses.