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    Magnetic Field in a Single Current Coil

    I understand that the magnetic field in a solenoid can be approximated as being constant as the length of the solenoid tends to infinity, but I was wondering if anyone could show me or point me in the direction of a derivation of the precise magnetic field at any point within a single loop of...
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    COV area under a curve

    So, If you've got two points and a given length of curve to 'hang' between them, what shape is the curve which minimises the area underneath it? For a curve which is almost the same length as the distance between the points, this would be a catenary, I think (a la famous hanging chain problem)...
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    Ring of light

    I was in the French Alps the other day, high in the mountains (not sure if this is relevant), and, on the night of a full moon, with mist in the sky, there was a circular ring of light around the moon. The ring subtended an angle about 5 times that subtended by the moon (that is to say, it...
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    Classic Problems

    I find it very interesting trying to solve the 'classic' kind of physics problems. The ones that Euler, the Bernouillis and co. bandied about, I've come across: The shape of a hanging chain The shape of a hanging elastic string The brachistochrone (the shape of a wire such that a bead...
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    Surface element meniscus - free body diagram

    Consider the free body diagram of a surface element of a water - glass meniscus in a vacuum. Along the line normal to the surface, the water pressure acts towards the vacuum, and the direction of the surface tension 'curvature force' depends on whether the surface curves like a 'u' or like an...