Recent content by Lomion

I'm getting confused over the formal definition of mutual inductance. I've googled and searched a lot of sites, but I still don't understand, so I'm hoping someone here can explain it to me in plain English! In our lecture, this was the formula given for mutual inductance: L_{12} =...

I know this sounds a bit stupid, but that's exactly what I'm confused about in my first example. Basically, I put a loop outside of the spherical shell. And depending on where I put the loop, it will either enclose the sphere, and hence have current going through it, or not enclose the sphere...

Hi all, This one's an easy one: What's the easiest way of telling whether a current is "enclosed" in a closed path or not? And how can I tell when a current effectively cancels itself out? For example, let's say I have a spherical shell with surface current density K [A/m], and I want to...

Convolution & Inverses Given an impulse response h[n] to a system, and the impulse response g[n] of the inverse system, why is h[n] * g[n] = \delta[n]? Where the * sign is used to denote convolution.

Are they not supposed to add up to 0? For example, in a dipole, you have +q and then -q, which adds up to zero. The textbook has been known to have errors, but I'm not sure my answer should be that far off from the given one. Does anyone have any links to a site that could give the equation...

Hi! Perhaps I should have made it clearer. It's a linear quadrupole because the charge in the middle (at the origin is -2q) while the charges on the top and the bottom are +q. The diagram itself was taken directly from the textbook, so it should be correct. Since it was badly drawn...

Can anyone tell me how to derive the equation for potential of an electric linear quadrupole? http://img142.exs.cx/img142/8715/quadrupole3tj.jpg My attempts yielded: V = \frac{q}{4\pi\epsilon_0} [\frac{1}{R_1} - \frac{2}{R} + \frac{1}{R_2}] V = \frac{q}{4\pi\epsilon_0} [\frac{RR_2...

Hello! This is a question from one of our past exams, and it's had me stumped for the past hour. The question states: The cylinder x^2+y^2=2x cuts out a portion of a surface S from the upper nappe of the cone x^2+y^2=z^2. Compute the surface integral: \int\int (x^4-y^4+y^2z^2-z^2x^2+1)...

An example in the book asks us to implement the XOR (exclusive-or) function using only 2-input NAND gates. So: f = x_1 \overline{x_2} + \overline{x_1}x_2 If we let \uparrow represent the NAND function. That means that: f = (x_1 \uparrow \overline{x_2}) \uparrow (\overline{x_1} \uparrow...

Geometry Question: Gradients & Normal lines & planes This is a question from a past midterm that I'd appreciate some help with. It deals with the gradient as a normal. I'm not having trouble actually obtaining the gradient, but I am having trouble with some of the geometry involved, so any help...

A double-pendulum, initially in a vertical position, is attached to a pin. The distance from the mass m (3.2 kg) at the top of the pendulum to the pin is 0.2 m, the distance from the mass m (3.2 kg) at the bottom of the pendulum to the pin is 0.4 m. A bullet of mass 0.05 kg is fired into the...