An alternator is a machine that makes electricity that keeps changing direction — what engineers call alternating current, or AC. The one most people meet is in a car: while the engine runs, the alternator makes power for the lights, the radio, and for putting energy back into the battery.

An alternator is a machine交流發電機是一種機器 that makes electricity that keeps changing direction會製造方向一直在變的電, — what engineers call alternating current, or AC工程師把這種電叫做交流電，也就是AC. The one most people meet is in a car大家最常遇到的是車上那個: while the engine runs當引擎在運轉時, the alternator makes power for the lights, the radio交流發電機會為車燈、收音機供電, and for putting energy back into the battery並且把電力補回電瓶

Though actually, everyday talk often just says generator for this, and in a garage that is usually what people mean — but in a careful science sense a generator can be a broader kind of machine, and the car part built for this job is an alternator.

Though actually不過事實上, everyday talk often just says generator for this日常說話常常就直接說generator（發電機）, and in a garage that is usually what people mean而在修車廠大家講的通常也是這個意思 — but in a careful science sense但嚴謹一點從科學角度來說 a generator can be a broader kind of machinegenerator可以是一種更廣泛的機器類別, and the car part built for this job is an alternator而車上專門做這件事的零件就是alternator（交流發電機）

When the car is off, the battery does the work; the alternator earns its keep while you drive.

When the car is off當車子熄火時, the battery does the work是電瓶在做這件事; the alternator earns its keep while you drive而你開車的時候，交流發電機才在發揮它的作用