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    Im not too sure about the (ii) part of this question. The mark scheme is very poor too and gives very little information (which is always the bloody case with A level mark schemes).

    I dont know what i can say about how the two fields interact.

    Can someone tell me what i am missing in my answer below? What bits are correct and what bits are wrong?

    The rod exerts a magnetic force upwards on the rod, since there is moving charge in the form of electrons passing through the rod, and these electrons are pushed upwards by the magnetic field and cause the rod to feel an upwards force as a result. The electrons exert an equal and opposite force down on the magnet, adding to the force on the electronic balance, hence increasing the reading.

    The total force acting on the mass balance is: mg + BIL

    You are not given the direction of the field but you know that the force is down. Fleming's LH rule with conventional current will tell you the orientation of the magnet. You know current direction and force so you can work out field.

    You have to judge from the marks available, (which we cant see) how much to say.

    BTW, your lack of answers may have been due to the poorly rendered image.
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Updated: February 19, 2016
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