The current required to be passed through a solenoid of 15   cm length and 60 turns in order to demagnetise a bar magnet of magnetic intensity 2 . 4 × 10 3   A   m – 1 is ________ A .

Step-by-step solution

The magnetic intensity is H = B μ 0 - M For M = 0 , it can be written H = B μ 0 = n i The data given is H = 2 . 4 × 10 3   A   m - 1 l = 15 × 10 - 2   m N = 60 Using the relation, n = N l and H = n i , the value of the current is, i = H n = 2 . 4 × 10 3 × 15 × 10 - 2 60 = 6   A