A semicircular loop of radius 1 m carries 2 A through its curved and straight sections as shown in a uniform magnetic field B = 1 T into the page. The magnetic force on the illustrated current-carrying conductor is 8N newtons (i.e., 8×N N). Find N.
Physics · Mixed Chapter
JEE Mains

Question

A semicircular loop of radius 1 m carries 2 A through its curved and straight sections as shown in a uniform magnetic field B = 1 T into the page. The magnetic force on the illustrated current-carrying conductor is 8N newtons (i.e., 8×N N). Find N.

Physics · Mixed Chapter

G1 Physics · Accepted Answer

Explanation: The resultant magnetic force on an open current segment in uniform B equals IΔr×B. The semicircular arc and straight diameter each run from P to R and each has |Δr|=2R. Thus their magnitudes add: F=2×(I×2RB)=2×2×2×1=8 N. Hence N=1.