A conducting wire MN carrying a current I is bent into the shape as shown and placed in xy plane. A uniform magnetic field B⃗ = -Bk̂ is existing in the region. The net magnetic force experienced by the conducting wire MN is :-

Question

G1 Physics · Accepted Answer

In a uniform field, the net force on any bent wire is F⃗=I( r⃗ at N - r⃗ at M )×B⃗. From the geometry, the end-to-end displacement has magnitude 6R perpendicular to B, so |F|=6BIR. Hence D.