elecromagnetism Definition and 15 Threads

At first, I derived that: $$\nabla \frac 1{\mu}=-\frac 1{{\mu}^3}\left((1-\beta^2)+\frac{\dot{\vec\beta}\cdot\vec R}c\right)\vec R$$ (dot means differentiation with respect to ##t'##). I assume this result is true because it gives valid result for magnetic field. To find electric field one...

So the formula for emk for a circuit is where f_s is caused by non emf forces like a battery. E is the electricalfield inside the circuit? v is the velocity of the circuit and B is the external magnetic field. I have difficulty understanding E. There are two "types" of electrical field one...

Imagine a charged sphere at the origin connected through an open switch to a vertical grounded wire. We wish to find an expression for the horizontal component of the electric field at a distance ##\mathbf{r}## from the sphere as it discharges. By using the Lorenz gauge condition: $$\nabla...

Assume that this is a case where by sheer coincidence, two sources of coherent single-frequency EM wave pulses with equal duration are both fired in opposing directions, with both carrying the same frequency and amplitude and orientation. These two waves meet head-on while moving in opposing...

I realize that the standard formula for the inductance of a solenoid (L = (μ₀ * N² * A) / l, where A is the cross sectional area, N is the number of turns and l is the length) is for solenoids with only one layer of wire. I thought I could find μ₀ using this simple formula, but it does not work...

clear clc u0= 4*pi*1e-7 %magnetic permittivity constant %simulation settings n=1000; v=zeros(1,1000); t = linspace(0,0.1,n); %railgun electrical properties R_wire = 0.1; %0.1 ohms of wire R_projectile = 2e-6; R_t = R_wire+R_projectile; V_cap = zeros(1,n); V_cap(1) = 500; % capacitor maximum...

The volumetric charge density is given as $$\rho(r) = \rho_0 \left(1 - \frac{ar}{R}\right)$$ What shall be the Electric field at any distance ##r## ? My approach was to directly use the coulomb's law and integrate with respect to volume. $$ \mathbf{E}(\mathbf{r}) = \frac{1}{4\pi\epsilon_0}...

So I tried to solve this using the Hertz potentials. I choose the magnetic one since this one corresponds to the magnetisation. Before I start let me note that I denote a unit vector with a hat, while ##{x,y,z}## are the Cartesian coordinates and ##{r,\theta,\phi}## are the spherical...

My set-up is the following: i have an iron bolt suspended on a string next to an electromagnet, of which I steadily increase the voltage and thereby the magnetic field. Supposing the force is linear with the magnetic field and dependent on the distance between the bolt and magnet. The exact...

Hello! Now i need a bit explanation, so "oscillating circuit" capacitator + coil in series. Let's look at this as infinite, without any loss. We get changing magnetic field and electric field. Capacitator discharges, current goes to coil increasing its magnetic field, then starts magnetic field...

Hello, im a bit confused about the right term in Faradays Law vs the right most term in Amperes Law. They both seem like terms corresponding to a resistance to change, similar to inertia. As in, the induced electric field from a changing magnetic field has an opposite direction compared to the...

TL;DR Summary: Need dielectric constant for given capacitor Given a 7.4 pF air-filled capacitor, you are asked to convert it to a capacitor that can store up to 7.4 mJ with a maximum potential difference of 652 V. Which dielectric in Table 25-1 should you use to fill the gap in the capacitor...

So I saw an article about the universe and lets say the article saied: the essence of the universe, which is impossible, as it has been proven that universal constants such as the gravitational constant and the speed of light indicate the existence of unified physical laws that govern the entire...

The reasoning I had was that in the horizontal direction, if the current flows into a node from the left, then it must flow into the node on the right so that that node has current flowing in from the left. Thus, the flow on the horizontal is always either from left to right or from right to...