Recent content by okami11408

Im sorry its sine not cosine.

Negative frequency is nothing but phase reversal. eg. sin(2pi(-f)t)=-sin(2pi(f)t)

Thanks you for the answers! Now I see that knowing power spectral density is useful, but why does the Fourier transform of power mean nothing? Because the Fourier Transform of p(t) shows power at each frequency, suppose I get sinc function from Fourier Transform p(t), it shows that most of a...

Normally, when we dealing with power signal in frequency domain we usually use power spectral density. My question is why is that? Why we define the power P(f) this way. http://img21.imageshack.us/img21/6786/powerec.jpg This makes no sense to me, Why don't we just Fourier transform p(t)...

I'm confused about this because voltage or potential difference is defined as work done by an external source in moving a unit charge from one point to another in an electric field. However, in circuit analysis things seem to be different because we measure voltage from V=IR. I want to...

I'm learning about an antenna theory and have a few question. According to the attached image. Can anybody explain what's going on in the image? I've done lots of calculation, but still have no idea what's going on. My question is 1. How dipole produce a loop of electric field...

That helps a lot! I really can't thank you enough, thanks a million! So, the electric flux density is a vector because it is sort of electric field, but through any medium. We need it because it can be used anywhere (in most of equation they use electric flux density instead of electric...

Thanks for the replies! However, I still confuse about what electric flux density really is. And why it is a vector since it's a density, because from what I know density is a scalar. Electric Flux is also a scalar as you clarified, electric flux density can't be anything but electric...

I know that the electric flux is a scalar quantity, but the concept of the Electric flux seems to confused me. If the electric flux density is a vector quantity, how come the electric flux is a scalar quantity? For example, I have the electric flux density: D=20i+2j. Isn't it means...

when you say L(1)=1/s, it means that 1 in time domain is 1/s in Laplace domain. Laplace domain is frequency domain of a function that already multiply with exponential decay.

The simplest way of understand Laplace transform is to understand Fourier transform. Laplace transform is Fourier transform of exponential decay multiply by the given function. This happened because we cannot Fourier transform some functions (the value goes to infinity) therefore we multiply...

Now I got it. Those resistor load our amplifier too. The reason why I confuse is I think "open loop" maybe something like we take the feedback circuit out of the circuit. Thank you so much :-p

This is my first post here. I'm currently learning about Negative feedback. Normally, When we want to know the open loop gain, we rewrite circuit(a) to circuit(b). My question is why do RE1,RF,RE2 from circuit(a) turn into what we see circuit(b)? what is a theory behind this? In...

This is my first post here. I have a problem dealing with Electric flux. According to Gauss's Law, to find electric flux we use equation: ψ=∫D dot dA, both D(Electric flux density) and dA(super small area normal to the surface) are vector quantity. Now this is what I confused, how...