Thinking about Science with David Hukins

Maxwell's equations describe the behaviour of electric fields and magnetic fields; a more detailed introduction appears in post 25.12. Equations (1)-(4) (highlighted above) are Maxwell's equations in vector notation. Here E is an electric field, B is a ma

This post is a sequel to post 26.4 so I suggest you read that first. In post 26.4, I expressed the Maxwell-Ampère law in terms of two definite integrals. In this post I am going to express it in a differential form. This is similar to what I did in post 2

This is a sequel to post 26.03, so I suggest you read that first. Maxwell realised that Ampère's law applied only when an electric current, in a conductor enclosed by a magnetic field loop, was constant. If the current changes, for any reason, in the firs

Ampère's law considers the electric current, I, enclosed by a magnetic field, B, that forms a closed loop. In post 25.16, we saw how to calculate the magnetic field surrounding an electrical current using the Biot-Savart law. Now we are going to consider

In post 18.6, I defined a simple harmonic oscillator as a system that was constantly exchanging potential energy and kinetic energy while conserving their sum. I then used the idea of a simple pendulum as an example to illustrate how this works. In post 2

I have read several articles about the increasing number of English parents who pay to send their children to private schools and then pay extra for private tuition to gain them a place at Oxford or Cambridge universities (often referred to collectively a

In post 25.10, I defined the magnetic field, B, caused by an electric current, I1, in a long straight wire, at a point given by a vector r, perpendicular to the wire, by where μ is the permeability of the stuff surrounding the wire, and i r is the cross p

In post 25.10, I used a special case of the Biot-Savart law to define magnetic field. This law is named after the French physicists Jean-Baptiste Biot (1774-1862) and Félix Savart (1791-1841). But in post 25.15, I described how magnets were known long bef

So far, in this blog, I have explained that magnetic fields are a result of an electric current (see posts 16.25 and 25.10). But that is not how they were discovered. The idea of a magnetic field came from the properties of permanent magnets (we usually c

Before you read this, I suggest you read post 25.13. Electromagnetic induction arises when a current flows in a circuit when it is in a changing magnetic field (post 25.13). Faraday considered that the current flowed because an induced voltage caused char