Electronics > Beginners
Understanding induced voltage
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ZeroResistance:
Case 1
I have a 100 turn coil wound on a rod of soft iron and I feed it some current such that one pole of the rod is now N pole and the another S pole. And I have another coil wound on this rod to read the induced voltage.
So first
a)
I move a soft iron rod towards the N pole and away from it in a reciprocating manner.
and then for another test
b)
I move a soft iron rod in a side by side like a clock arm moving past a hour digit. So the soft iron rod will first be aligned with the N pole then swing to the left then back to the center and then to the right and again back to the center.
Should I expect AC to be generated in this way or only pulsed DC? In both the sub cases (a) and (b)
Is there any way, any program that I can visualize this?
Doctorandus_P:
You are unlikely to see any voltage generated.
For generating voltages you need a moving coil in relation to an externally generated magnetic field.
Moving iron, (or any conductor) in a magnetic field will generate eddy currents, but that is another phenomena.
ZeroResistance:
--- Quote from: Doctorandus_P on January 27, 2019, 07:37:02 am ---You are unlikely to see any voltage generated.
For generating voltages you need a moving coil in relation to an externally generated magnetic field.
Moving iron, (or any conductor) in a magnetic field will generate eddy currents, but that is another phenomena.
--- End quote ---
Wouldn't the moving rod change the flux linkage in the fixed rod there by change the flux in the fixed rod as it is approaching it and so there is an induced voltage?
Doctorandus_P:
I'm having some doubts here, you might see some small effect :scared:
However, when you're looking at electric motors they always have 2 separate coils, or a coil and a permanent magnet. (The cage in a squirrel cage induction motor is also a coil).
10 minutes later...
So I grabbed an electromagnet with a 120Ohm coil and a 120Ohm resistor and put 20V over it, which resulted in a current of 80mA. I used the resistor to have a higher (and symmetrical) impedance from the 20V power supply.
Adjusted my rigol scope to AC coupling to see differences on the 10V over the coil and then I started pulling the iron core out of the magnet like a madman and pushing it back.
Whenever I pulled the iron core out of the magnet the voltage over the electromagnet dipped by 4V, and when the iron core was pushed back into the magnet I had a positive spike on the elctromagnet of also around 4V. Such an even has a duration of around 30ms to 40ms.
So you are right. A change in the amount of iron within the inductor changes the flux and with that you see voltage & current spikes.
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