A uniform circular wire of radius a has an electric current i entering and exiting through diametrically opposite points. Passing through the centre at a speed v , a charged particle q travels along the axis of the circular wire. What is the magnitude of the magnetic force acting on the particle at the instant it crosses the centre?

Step-by-step solution

When the current i enters the uniform circular wire at one point and exits at the diametrically opposite point, it divides equally into two semicircular paths. The current in each semicircular part is i 2 . The magnetic field at the centre due to the first semicircular part is B₁ = ₀ (i/2) 4a , directed perpendicular to the plane of the loop (say, inwards). The magnetic field at the centre due to the second semicircular part is B₂ = ₀ (i/2) 4a , directed perpendicular to the plane of the loop in the opposite direct