Voltage drop by resistor
 

I have a 6 volt supply I need to drop to around 3-3.5 volts any quick idea what value resistor I could use. Thanks

An Application of Ohm's Law should help you with this.

V=I/R

I hope this helps.

Well that would be a lot of help if I could get it right

Just Google Ohm's Law, there are like 3 different formulas that you can use for voltage dropping calculations, depending on the information you have.

You are probably going to need to know what current is through the circuit too for calculations. (There's other things like power that can be used in lieu of current with the right formula).

This is not correct.

V= I x R

Which can be re-arranged as:

I = V/R

or

R = V/I

It would help if the OP gave us an idea of what he's trying to do. A resistor might be the right way to drop the voltage. In other applications a voltage regulator chip might be better.

If it's a heater supply and the source is AC a diode might even suffice.