Question

If a circular loop carrying current I, then the direction of the magnetic field at the centre with the help of magnetic lines of forces will be?

Answer 1

Consider the circular loop caries the current in anticlockwise direction as observed by the observer "O". Therefore, this face of the loop will behave as North pole and magnetic field lines are directed towards the observer.

The correct is convex mirrro

Answer 2

You can determine the direction of magnetic field lines by performing the apparatus used in following experiment 

I)The direction of magnetic field changes when the direction of flow of current is reversed  or vice versa 

II) The strength of the magnetic field increases with increase in current

III) The strength of the magnetic field at the centre of a circular coil carrying current is proportional to the number of turns in the coil (n).

In result , when  we increase the turns, the magnetic field strength also increases. As we go away from the wire, the strength of the magnetic field decreases, and the concentric circles grow larger in size

IV) The strength of the magnetic field is inversely proportional to the radius of the circular coil as a result  the field strength reduces as the radius of the coil.  increases