diode
a device which changes ac to dc is known as 'conevrter' a device which changes dc to ac is known as 'inverter'
An alternator is a device that converts DC (direct current) to AC (alternating current). If you need to convert AC to DC, then you need a rectifier.
an Inverter is an electrical device that changes DC to AC.
An alternator produces AC current but it is converted to DC by the rectifier inside the alternator.
Most automotive applications use DC, although the alternator is an AC device which uses a rectifier to produce DC. http://en.wikipedia.org/wiki/Direct_current
A rectifier is an electronic device that changes an AC voltage to a DC voltage.
Alternator = AC electricity Generator = DC electricity
Turn the DC generator inside out and you have an alternator .
The engine itself emits nothing. The alternator does. The alternator emits AC, but it is converted to DC.
The indicater meter is a DC device, so the rectifier changes AC to DC. A meter could not respond to AC.
the answer is Rectifier. it converts ac voltage into dc which can apply to the dc device
Personally, AC and DC drives are quite easy to understand. DC drive is a device that uses AC as a power source to control the DC device.