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
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.
Calculating Inductance? Watch
- Thread Starter
- 20-01-2010 19:30
- 21-01-2010 00:29
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.