JEE MAINS PHYSICS QUESTION SEPTEMBER 2020 which of the given option is correctly represent the deflection of the needle in Galvanometer?
Answers
A bar magnet moves with constant velocity as shown in figure through a coil. which of the following option is correctly represent the deflection of needle in Galvanometer.
solution : option (2) is correctly represent the deflection of needle in the galvanometer.
explanation : according to Faraday's law of induction, when we change the magnetic flux, an induced current produces in the coil.
so change in flux needs to produce induced current.
case 1 : here bar magnet is entering within the coil with constant speed, so flux will change and hence an induced current will produce in the coil so that galvanometer will deflect in a specific direction. ( let it deflects N - W direction)
case 2 : here magnet is completely inside the coil so flux will never change. then induced current must be zero. cause galvanometer will never deflect.
case 3 : here magnet is now moving out so the flux will change and current will be induced in the coil and galvanometer will deflect but in opposite direction of first case i.e., N - E direction.
now you can check, you definitely get option (3) is appropriate choice.