Trivia: What electrical implement used to be called a “dynamo”?
An extension cord
The correct answer is A generator
So why is this answer correct? : At one time, a generator was called a dynamo. This was back in the 1800s, when German engineer Werner von Siemens successfully constructed the very first generator (although several other researchers were working on similar experiments at the time). His was the standard until Belgian engineer Zénobe Théophile Gramme invented a better one in 1867.