COMEDK20269 May 2026Morning ShiftPhysicsMagnetic Effects of CurrentActual
The magnetic field at the centre of a wire loop formed by two semicircular wires of radii r₁ = 3.14m and r₂ = 6.28m and carrying a current of I =2A is:
Options
- A3 10⁻⁷ T
- B6 10⁻⁷ T
- C4 10⁻⁷ T
- D2 10⁻⁷ T
Correct answer
A. 3 10⁻⁷ T
Step-by-step solution
The magnetic field at the centre of the loop is the vector sum of the magnetic fields produced by the four segments of the wire: two straight segments and two semicircular arcs. For the straight segments, the line of action of the current passes through the centre of the loop. Therefore, the angle between the current element d l and the position vector r is 0 or . The magnetic field due to these segments at the centre is zero. For the semicircular arcs, the magnetic field at the centre is given by B = ₀ I 4r . The