Explain the phenomenon of electromagnetic induction. Describean experimentto show that a current is set up in a closed loop when an external magnetic field passingthroughthe loop increases or decreases.

Explain the phenomenon of electromagnetic induction. Describean experi

1.	Explain the phenomenon of electromagnetic induction. Describean experimentto show that a current is set up in a closed loop when an external magnetic field passingthroughthe loop increases or decreases.
Answer» Solution :The phenomenon where a CHANGING magneticfield in a conductorinduces a current in anotherconductor is called electromagnetic induction. Experiment to showthat a current is SET up in a closed loop when an external fieldpassing through the loop increases or decreases : 1] Wind insulated copper wire on an insulating cylinder (made of cardboard or thick paper) as two COILS - coil 1 and coil 2 having large number of turns (say 100 and 50) as shown. 2] Connect coil 1 (having more number of turns) to a battery and plug key, and coil 2 to a galvanometer. 3] Insert the plug key and observe thedeflection in the galvanometer .Itshows momentary deflectionin one direction . 4] Now removethe plug key. Galvanometeragain shows deflection but in the oppositedirection. Inference : WHENEVER electric current through coil 1is changing (increasing or decreasing) , magnetic field associated with it alsochanges accordingly. Thiscause changes INTHE magnetic field experienced by coil 2 and hence a current is induced in it which is observed as a deflectionin the galvanometer.Thus, changing magnetic filed inducesa current in a closesloop.