CBSE Class 10 Science 2020 · Paper 31/5/3 · Question 24

(a) The pattern is shown in the figure. Near each point where the loop crosses the paper, the field lines are concentric circles around the wire; they grow larger towards the centre of the loop, and at the centre they are straight lines parallel to the axis of the loop, all pointing the same way. Field lines never cross, and the field inside the loop is stronger than outside. (b) Right-hand thumb rule: imagine holding the current-carrying conductor in the right hand with the thumb pointing in the direction of the current; the fingers then wrap around the conductor in the direction of the magnetic field lines. Applied to every part of the loop, it gives the direction of the field inside and around the loop.