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    Work/Energy and Parallel Current-Carrying Conductors (Conceptual Question)

    Faraday's law states that a changing magnetic field induces an electric field. So, the moment the current is allowed to pass in the two wires, a magnetic field is created in a region where there was none previously. This change induces an electric field which is responsible for the work done on...
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    Photon absorbing cloaking device

    Another relevant column can be found in the french science magazine "Science & Vie" (October 2008 No. 1093, p49) for those of you who speak some french. The metamaterial is said to be able to "bend" light incident on it for wavelengths around 660 nm. The material is made out of silver nanowires...
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    Mechanics & physics,can anyone explain the scenarios?Very practical Questions?

    I think that Q4 = C because the the magnetic field which is induced by the current flowing in the wire is not in any of the direction described in A or B (It is actually normal to the plane of the screen. Also, Q3 = A because the torque of a force acting at a larger distance from the center of...
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    Electric field lines

    Do you want the field lines in 3D or just in the plane of the arc?
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    I'm new to optics: need help on lens please!

    I have a more or less related question. Can one focus an object on the slit of a spectrometer by positionning the object close to the lens (<focal length) and slit at infinity (~150m)?