There isn't one single physicist who "discovered" the dynamo and generator. The understanding and development of these devices was a gradual process involving many individuals over several decades.

Here's a breakdown of key contributors:

* Michael Faraday (1831): Faraday's groundbreaking work on electromagnetic induction laid the foundation for the dynamo and generator. He discovered that a changing magnetic field could induce an electric current, a phenomenon known as electromagnetic induction.

* Hippolyte Pixii (1832): Pixii built the first magnetoelectric generator, a device that used a rotating magnet to produce an alternating current.

* Werner von Siemens (1856): Siemens developed the first self-exciting dynamo, a device that could generate its own magnetic field, making it more efficient and practical.

* Zénobe Gramme (1871): Gramme invented a direct current dynamo that was significantly more efficient and reliable than previous designs. This paved the way for the widespread use of electricity in industry and everyday life.

So, while Faraday's work is considered the most crucial, many other individuals contributed to the development of the dynamo and generator. It's a classic example of how scientific progress is often the result of cumulative efforts.