Hi everyone,
>
>I took part in a competition of my college's electronics club to build
>an electromagnet under £100, with the strongest and cheapest one
>winning.
>
>Approach #1:
>I bought a 500W ATX power supply and used the 12V 35A
There is no 12V/35A lead on a 500W ATX supply...
lead to energise
>an electromagnet. I used a full 100m length of 0.8mm thick enameled
>copper wire - that length had a resistance of about 5 ohms.
So five ohms, 12 volts (if you really used five volts), gives you how many amps? Com'on, Ohm's law here--about 2.4 amps, maybe? And that would be about how many watts? Almost 29 watts. I'm sure it was totally unimpressive, you needn't have even bothered had you done your homework!
The wire
>reel in the as-bought state conveniently had both leads exposed.
>
>I put a 10mm steel hex bolt through the reel's centre hole as the core
>material. The electromagnet was feeble and was no where even close
>enough to carrying its own weight :(
>... Remainder snipped...