7th of September 2015

to derive the magnetic field inside a current carrying solenoid, when we imagine a loop to be taken say pqrs we let its one side to be out of the magnetic field, why?( if we do take it as such answer would be different )

Alice - CBSE - Class XII Science

Monday, September 07, 2015 at 13:59:PM


Hi Alice, 

This is done because we use Ampere's law to derive the magnetic field.

Now, according to Ampere's law, the magnetic field due to a closed amperian loop is zero.

So, if the entire loop is placed inside, no current will flow through the loop and we will not be able to find B.

Hence, half of the loop is kept inside and half of it is outside.

Monday, September 07, 2015 at 18:13:PM