i was at this website http://www.rc-cam.com/microszr.htm and it shows how to transfer parts from a mini car, and put some of them in an r/c airplane. on that page somewhere, he talks about making your own actuator coils, and he wanted to make his 60 ohms, and somehow, he was able to measure the ohms so that he would know how much he had. is there any formula to measure ohms on a coil of an acuator?

You need an Ohm meter, or a multi-meter to read the ohms. Ohms is resistance to current flow from one side to the other. You can add resistors to boost the ohms, but that is probably not what he was doing.

Ohms can be resistance or impedance. Impedance is like resistance, except it applies only to an alternating current. A coil is simply a winding of wire, with or without a core. The wire will offer very little resistance to direct current or low frequency current, but its impedance will increase as the frequency of the alternating current goes up. 60 ohms of resistance would take a pretty long piece of wire, but 60 ohms of impedance could be very small physically, depending on presence or absence of a core (an actuator would normally be cored), number of turns and frequency of current. This is hardly a simple answer, but it's a lot simpler than a course in AC electricity.

You can measure resistance with an ohm meter but you can't measure impedence. You would need a specialty meter that generates an alternating current and then measures the voltage drop induced by the coil you test. I have such a meter that I use in my sound equipment installation business. It wasn't cheap or useful to the average modeler.

You could put voltage to it. Measure the current with an ampmeter and divide. R (resistance)= E(voltage) divided by I (current). Not the best way to go about it. Since you're talking about R/C the voltage will be DC. So there's no reason to get into impedence. Just pick up a cheap multimeter at your local hardware store as they will generally measure resistance.

In spite of a few inaccuracies on definition of impedance above, what I think the gentlman who wants a 60 ohm actuator core means is that he uses a length of magnet wire that literally measures out as 60 ohms impedance (that is DC impedance which is ohms as measured with an ohm meter). You need to know the gage of wire he is using and then look up the ohms/foot of that gage and that type of wire in table to see how many feet of wire he is winding into the actuator. The radio amateaurs manual has that information as do many engineering text books. For those questioning definitions, ohm is impedance always but impedance can be more than just the ohmic value, i.e. capacitive and inductive reactance to ac signals which add to the dc component usually stated as "ohms" and effects only the ac currents.