Electromagnetic Induction. 1st day, 2nd day. Hello. Mr. Hans Christian Oersted. Battery. Switch. Magnetic compass needle. Conductor. Electric current. Needle deflects. This indicates presence of magnetic field. Electric current. Needle deflects. This indicates presence of magnetic field. This proves that electric current produces a magnetic field. Electric current : Magnetic field. Magnet : Electric current. Is this possible? Galvanometer. Magnet. Coil. Needle is not deflecting. That means no current is being induced. Motion of the magnet is causing the needle to deflect. Now, let me keep the magnet fixed and move the coil. I can still see deflection. Current is induced in the coil due to relative motion between the magnet and coil. When I moved the magnet away, needle deflected in the opposite direction. That means the current is now being induced in the opposite direction. Now, let me try to reverse the poles of the magnet. The deflection reversed when the pole was reversed. North pole going inside the coil, deflection towards right. North pole coming out of the coil, deflection towards left. South pole going inside the coil, deflection towards left. South pole coming out of the coil, deflection towards right. Let me try to move the magnet faster. Faster motion of magnet. Faster motion : Faster needle deflection : Rate at which current is induced is more. Conclusions of experiment. Relative motion: Current is induced due to relative motion between the magnet and coil. Pole reversal: Deflection reverses when the poles of the magnet are reversed. This direction of deflection shows the direction of flow of current. Speed: Faster motion of the magnet or coil causes a faster deflection, that is, rate at which the current is induced is more. Faraday’s law of electromagnetic induction. This production of electric current across a conductor when exposed to a changing magnetic field is known as electromagnetic induction. The End.