The correct answer to the question is - He discovered electromagnetic induction after seeing a changing magnetic filed generate an electric current.
Step-by-step explanation:
Before coming into any conclusion, first we we have to understand electromagnetic induction and some phenomenon related to electricity and magnetism.
When current will flow through a conductor, it will produce a magnetic field around it . Any magnetic compass placed near to it will be deflected due to the magnetic field produced by the current carrying conductor. This experiment was done by Oersted .
Electromagnetic induction is the process of generation of induced current in a circuit or coil when the magnetic flux associated with that circuit or coil changes. Here, a changing magnetic field will produce an electric current.
Let us consider that induced emf is denoted by
Faraday's law states that the induced emf is directly proportional to the rate of change of magnetic flux.
Mathematically
The negative sign is used due to the fact that the direction of induced emf is opposite to the cause producing it.
Hence, the correct option will be C i.e he discovered electromagnetic induction after seeing a changing magnetic field generate an electric current.