The source of electric current is referred to as:

AC generators are devices that transform mechanical energy into electrical energy.

The output waveform of this electrical energy is a sinusoidal alternating current.

Gas turbines, steam turbines, and combustion engines are often the sources of this mechanical energy.

Faraday's law, which describes electromagnetic induction, is the basis for how AC generators operate.

Electric motors are the machinery that transform electrical energy into mechanical energy.

Faraday's Law is the foundation of how an AC generator operates.

Electrical energy is produced by AC generators from mechanical energy.

A sinusoidal waveform represents the energy that is produced (alternating current). As a result, choice 2 is right.

An instrument called an ammeter is used to gauge the circuit's current flow.

It has a minimal resistance, ideally none.

Ammeters are connected in series to allow the entire circuit current to flow through and be measured.

Galvanometer: A device that measures and detects electric current using electromechanical principles.

An actuator is a galvanometer.

In reaction to an electric current running through the coil in a constant magnetic field, it creates a rotating deflection.