To Michael Faraday and James Clerk Maxwell

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There is no better way to finish the first year of conversations on relativity and electromagnetic topics than to talk of the contribution of Michael Faraday and James Clerk Maxwell to the study of electricity and magnetism. The Royal Institution of Great Britain in Albemarle Street in London has an Electrical and Magnetic Museum devoted to Michael Faraday. Faraday performed his investigations at the Royal Institution and his original equipment is on display. Faraday's lines of electric and magnetic force permeate the thinking of physicists and electrical engineers. While at nearby King's College James Clerk Maxwell used Faraday's lines of force in his Dynamical Theory of the Electromagnetic Field, published 150 years ago. Maxwell's four equations, and their solutions, give us a complete description of the electromagnetic field. As an example, imagine that in a rectangular region of space an electric field E exists whose x-component is constant and whose y-component is proportional to the x coordinate. Many physics and engineering students do not realise that a perpendicular time varying magnetic field B must accompany this E field. Why?

As the Earth Turns

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The Science Museum in London has a marvellous long swinging pendulum that appears to change its direction during the day. Some books say that the pendulum keeps swinging in the same plane in space. Is this true in London? How do we explain the shift in the position of the pendulum during the day?

“At the north pole the direction of the swing of the pendulum does not change in space, so the pendulum shows the Earth turning beneath it in 24 hours. Here in London it is not so simple; the direction of the pendulums swing moves around the circle in about 30.5 hours. As we travel towards the Equator the direction of swing moves more slowly, until at the Equator no movement is seen. In the southern hemisphere the direction of swing moves in the opposite direction.”
— Description of Foucault's pendulum at the Science Museum, South Kensington, London