electric charges ammeters are devices that are used to measure electric current. They measure the rate that electric charges move through a *blank* called an ampere, or amp The unit of AMP

Question

Fill in the blank

It's not conductor
It's not circuit

Answer 1

The unit of electric current measured by ammeters is called an ampere, or amp, and it measures the rate that electric charges move through a conductor. Since "conductor" is not suitable for your blank, an alternative term you could use is path.

So the completed sentence could read:

"They measure the rate that electric charges move through a path called an ampere, or amp."