The difference between an ammeter and galvanometer

Before we can discuss Fleming's right-hand rule we need to understand the difference between an ammeter and a galvanometer.

Ammeter

An ammeter is a measuring instrument used to measure the magnitude of the current in a circuit. Electric currents are measured in amperes, hence the name ammeter.

Galvanometer

A galvanometer measures both the direction of the current and its magnitude.

Galvanometer shows 1.5 amps positive.

Galvanometer shows 1.5 amps negative.

Note: A galvanometer can not measure A.C. current because its pointer moves based on current direction resulting in no net deflection over a full cycle. The alternating current causes the coil to experience rapid, alternating forces, causing the needle to vibrate or stay at zero. 

Ammeter can measure Alternating current and Direct current. 

Galvanometer can only measure direct current.