An ammeter is used to measure the current in a wire. If an ammeter indicates a current in a wire,
what can be said about the charges in the wire?

"The ammeter will read negative when power is being used and the engine is off. It will read positive when the engine is running, and charging. If it never goes to positive, something is amiss." Hope that helps! :)

Explanation:

"An ammeter is an instrument for measuring either direct or alternating electric current, in amperes. An ammeter can measure a wide range of current values because at high values only a small portion of the current is directed through the meter mechanism; a shunt in parallel with the meter carries the major portion."

i think its