BITSAT2018PhysicsMagnetic Effects of CurrentActual
A current i flows through a loop as shown in figure. The magnetic field at the Centre O is
Options
- A7 μ o i 12 r acting downwards
- B5 μ o i 12 r acting upwards
- C7 μ 0 i 12 r acting upwards
- D5 μ 0 i 12 r acting downwards
Correct answer
D. 5 μ 0 i 12 r acting downwards
Step-by-step solution
The angle, subtended by arc D E at O is π 2 and F C at O = 3 π 2 the effective magnetic field at O is B = B D E + B F C = μ 0 i 4 π 3 r × π 2 + μ 0 i 4 π r × 3 π 2 = μ o i 8 r 1 3 + 3 = 5 μ o i 12 r acting downwards