so if i wrap 200ft of #30 wire and use a 5v battery that would be... 250mA.
But the question for that would be ... the 250mA would be the output current comming out of the coil? Or the current it uses?
look at the coil as a simple resistor when it is used in DC circuit. So, if the 200ft of #30 wire is 20R then current flowing trough your coil is I = U/R = 5v/20R = 0.25A
If your whole circuit is battery and coil, then the current flowing trough the circuit is 250mA .. not sure what you mean by "coming out of the coil", the current is flowing trough the coil, going in on the one side and coming out on the other side
... while current is flowing the coil will generate magnetic field.
When you "stop" current from flowing, for example by using the switch, or disconnecting the battery, the coil will generate strong EMF pulse that can be few hundred volts (low current, short time) that can burn out any transistor or IC in the circuit, that is why you need the back EMF protection diode (just add reverse polarised signal diode parallel to the coil) so that EMF does not cause havoc in the circuit
Also whats the end voltage or is it the same?(voltage out of coil)
Voltage were? Voltage on the end of the coil will be the one you apply to it if that is the only element in the DC circuit (apart from the power supply).. As I said, consider that coil as regular resistor if the circuit is DC. If circuit is AC then it gets bit more complex
How would i change the current to voltage ratio?
I = U/R
U/I = R
R = U*I
What is the constant and what you can change ?
If your voltage is static (1.2V battery for example) you can increase current by reducing the resistance of the coil (less wire) or you can decrease current by increasing the resistance of the coil (more wire)...
Because i hear you can use a inductor to take 5 volts and make it like 50v but you lose some current OR you can take 5v @ 1A and change to 2A but lose voltage... How would this work? I know it has to be 2 coils i think.
You cannot make that using simple DC circuit
you will have to make a "voltage pump" or whatever is the real name for it, or so called DC DC converter circuit.
here is a very good link with explanation, example circuits and graphs
**broken link removed**
Also if i wrap a piece of metal than can be magnetized with this wire and make a electromagnet would it work against other metals only or both other metal and magnets.
You need to wrap wire around the metal, not metal "with" wire to make it magnetised. The amount of "force" magnet will have towards other materials depends on their magnetic properties
Magnetic properties of materials
Magnetism - Wikipedia, the free encyclopedia
hope this helps