How did Micheal Faraday discover the magnetic theory and when?

Faraday made his first discovery of electromagnetism in 1821.  He took the work of Oersted and Ampère on the magnetic properties of electrical currents as a starting point and in 1831 achieved an electrical current from a changing magnetic field, a phenomenon known as electromagnetic induction.

Explanation:

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

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