NTA Abhyas JEE Main2020PhysicsMagnetic Effects of CurrentPractice
The magnetic field at the centre of a current-carrying loop of radius 0.1 m is 5 5 times that at a point along its axis. What is the distance (in m ) of this point from the centre of the loop?
Correct answer
0.2
Step-by-step solution
We know that, B c e n t r e B a x i s = 1 + x 2 r 2 3 / 2 Given that, B c e n t r e = 5 5 B a x i s B c e n t r e B a x i s = 5 5 ∴ 5 5 = 1 + x 2 0.1 2 3 / 2 On squaring both sides, we get 25 × 5 = 1 + x 2 0.1 2 3 125 3 = 1 + x 2 0.1 2 ⇒ 0.01 + x 2 = 0.05 ⇒ x 2 = 0.05 - 0.01 ⇒ x 2 = 0.04 ⇒ x = 0.2 m