Download: hilaroad.com/video Instructions for constructing and electromagnet and an investigation of magnets and the relationship between electricity and magnetism.
I noticed that even when the circuit was broken, the nail didn't lose its magnetic character. 9:20. What's the explanation for this? Does it take time for an electromagnet to lose its magnetic lineament, once the circuit is broken?
What you saw there is called 'residual magnetism'. Some of the magnetic flux remains in the iron core (nail) even after the coil current has been disconnected. This occurs because it is possible to magnetise certain materials.
The North end of a magnetic compass needle is the "North Seeking Pole", ie. it is attracted to the North Pole of the Earth. This is how the north pole of a magnet is defined. You may recall that with magnetic poles "opposites attract", (North attracts South) so to add to the confusion we must have a south "magnetic" pole at the North End (Pole) of the earth! If this isn't confusing enough, apparently every now and then (thousands of years) the earth's poles reverse!
The 1.5 volt alkaline AA battery has an internal resistance, this combined with the resistance (very small) in 5 meters of 28 gauge wire reduces the current flow so the coil does not overheat. A battery with a lower internal resistance or higher voltage would cause the coil to get too hot.
wait a second.. at 8:07 wouldnt the compass be the south and the other be the north? Because the compass attracts to the opposite? The red end (which finds north) would have have to be south because it attracts to the north. If im wrong please someone explain?
does it matter if the wire closest to the flat part of the nail is connected to the positive end of the battery and the wire closest to the pointy end of the nail is connected to the negative end of the battery? i really hope someone could answer that.please?
thanks man; i always wondered which way the current flowed from a wire!; but can u tell me if this statement of mine is correct: "the north pole(of the electromagnet)lacks electrons(positively charged)."; thanks so much!
As mentioned in the video this electromagnet must use a 1.5 volt AA battery, even with this small battery the coil will get very warm. A bulb in series would probably reduce the strength of the magnet considerably.
That looks very much like a short circuit. I think you would flatten the battery very quickly. It would be safer to add a 1.5 volt light bulb in series to keep the circuit safe.
when finding out the polarity of the electromagnet by checking it against the compass, u said that because the north pin of the compass was attracted to that end of the nail, it must be the south side, but surely the pin on the compass that points north must be south, so that it attracts to north. or am i going mad.
BTW all, there is no such thing as a real short circuit. All electrical conductors will have some resistance. A very small resistance such as this copper-wire just means that a lot of current will run. This will result in more heat being generated. Another important fact when working with electricity is that the hotter a conducting material becomes the more resistance it will get. So "shortcircuiting" a battery will cause higher internal resistance in the battery and more resistance in the wire
silverbull : the electricity is induced into the nail and becomes electromagnetism, if two insulated wires are wrapped on the nail you have made a transformer and the electromagnetism is reinduced and becomes electricity again,at this point the nail is no longer a magnet it's potential being disipated
