ARRL Technician Practice Exam

What reading would an ammeter calibrated in amperes show when measuring a 3000-milliampere current?

1. 0.3 amperes

2. 3 amperes

3. 30 amperes

4. 300 amperes

The correct answer is: 3 amperes

When measuring current, the unit of amperes (A) is often expressed in milliamperes (mA), where 1 ampere equals 1000 milliamperes. Therefore, to convert milliamperes to amperes, you can divide the number of milliamperes by 1000. In this case, you have a current of 3000 milliamperes. Dividing 3000 by 1000 gives you 3 amperes. Thus, an ammeter calibrated in amperes would show a reading of 3 A when measuring a 3000 mA current. This conversion is fundamental in electrical measurements, ensuring you can accurately interpret the values being measured depending on the unit used.