# Electrical engineering circuit analysis

• circuit_boy
In summary, the solution to question 1 is incorrect because rms is calculated using the mean instead of the square.
circuit_boy

## Homework Statement

Question 1: http://img690.imageshack.us/i/79806671.jpg/

Question 2: http://img833.imageshack.us/i/48920688.jpg/

V=IR, P=I^2R

## The Attempt at a Solution

Answers to Question 2 Part 1 :http://img545.imageshack.us/i/img0001e.jpg/

Answers to Question 2 Part 2 :http://img94.imageshack.us/i/img0002te.jpg/

Here are my answers for Question 2, if the solution is too long for you to bother with =D
a) Vth = 13V, Isc = 13A, Rth = 1Ohm
b) Vx = 12V
c) Vx = 12V
d) 8 watts, 2 watts, and 12 watts
e) Independent sources 16V and 10V absorb power, dependent source 1.2Vx delivers power

Feel free to give me any inputs! Your help is really appreciated!

At t=3, Q=5. How do you get a negative current?

Since Q/T = I

We can say that taking the derivative of Q with respect to T will yield I, which is actually the gradient of Q and T, or of the graph.

From t=2 till t=4, gradient is negative, hence yielding a negative value. Are there anymore errors that you have spotted in the solution?

circuit_boy said:

## Homework Statement

Question 1: http://img690.imageshack.us/i/79806671.jpg/

[...snip...]

## The Attempt at a Solution

In the future, please post only one problem per thread (different questions related to the same problem are okay, but just don't post completely different problems). It gets really confusing if people are trying to help you with different problems all in the same thread.

So for "Question 1" (actually, Problem# 1), your solutions to parts A and B are correct.

Part C, the rms current is incorrect.
For RMS,
(1) First take the square of the function
(2) Find the "mean" of that squared function, i.e. the average of the squared function. This generally done by integrating the squared function (i.e. finding the area under the curve of the squared function) and then dividing by the time.
(3) Take the square root of whole result.

In your particular problem, you didn't find the mean correctly. (The mean of a and b is not a/2. The mean is (a + b)/2).

More generally, rms for a continuous function is:

$$f_{rms} = \sqrt{\frac{1}{T_2-T_1}\int_{T_1} ^{T_2}[f(t)]^2 dt}$$

Last edited:
I see, the answer would be 5 then? Thank you for your input, try to have a look at question 2 too, thank you!

Last edited:

## 1. What is electrical engineering circuit analysis?

Electrical engineering circuit analysis is a branch of electrical engineering that deals with the study and analysis of electrical circuits. It involves the application of mathematical, scientific, and engineering principles to analyze and design electrical circuits.

## 2. What are the basic components of an electrical circuit?

The basic components of an electrical circuit include a power source, conductors, resistors, capacitors, inductors, and switches. These components work together to allow the flow of electrical current and the conversion of energy in a circuit.

## 3. What is Kirchhoff's Laws and how are they applied in circuit analysis?

Kirchhoff's Laws are two fundamental principles in electrical engineering circuit analysis that govern the behavior of electrical circuits. The first law, known as Kirchhoff's Current Law, states that the algebraic sum of currents entering and exiting a node in a circuit must equal zero. The second law, known as Kirchhoff's Voltage Law, states that the algebraic sum of voltage drops in a closed loop must equal the voltage supplied to that loop.

## 4. What is the difference between AC and DC circuits?

AC (alternating current) and DC (direct current) circuits differ in the direction of the flow of electrical current. In DC circuits, the current flows in one direction, while in AC circuits, the current changes direction periodically. Additionally, AC circuits typically use sinusoidal waveforms, while DC circuits use constant voltage or current.

## 5. How is Ohm's Law used in circuit analysis?

Ohm's Law is a fundamental principle in electrical engineering that relates the voltage, current, and resistance in a circuit. It states that the current through a conductor is directly proportional to the voltage across the conductor and inversely proportional to the resistance of the conductor. This law is used in circuit analysis to calculate the unknown values of voltage, current, or resistance in a circuit.

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