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    For my Advanced Higher Physics investigation I will be doing a series of experiments involving inductors.
    I want to include a section in my investigation about back emf, and I want to be able to calculate it.
    The formula I have is that

    back emf = -inductace x (dI/dt)

    Just wondering how I should go about calculating the inductance of my home made inductor?
    I have found several online "inductance calculators" which claim to do this but I am dubious about these and would rather do it myself if possible.

    The wikipedia page on inductance states that

    L= Nphi / current

    http://en.wikipedia.org/wiki/Inductance#Self-inductance

    Could I potentially do something like measure the magnetic field with a hall probe and relate this to magnetic flux by knowing the area that I measured it over?

    Or maybe put a voltmeter across an inductor in a circuit, switch on/off the current and see how the back emf affects this somehow?

    Any help will be much appreciated, I'm getting pretty desperate with this investigation.

    Thanks.
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    you could put the inductor in series with a switch, d.c. power supply and resistor.

    Look at the p.d. across the resistor when the switch is closed, preferably with a storage oscilloscope or data logger.

    The inductance can be worked out from the slope. E = - L dI/dt where E at the start will be equal and opposite to the supply voltage.

    You could also use an a.c. power supply and measure the impedance of a circuit with your inductor and a resistor. From this you can work out the inductance.

    You could put it in a circuit with a capacitor and find the resonant frequency from which the inductance can be calculated.

    This is all pretty standard stuff which you should find in a good textbook.
 
 
 
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