A charged particle enters the magnetic field at P and emerges at Q moving parallel to its direction of motion at P. If r₁ and r₂ are the radii of its circular paths in regions 1 and 2 respectively, which relation is correct?

Question

G1 Physics · Accepted Answer

In each region, radius r=mv/(qB), so r₁B₁=r₂B₂. Geometrically the equal-tangent condition shown gives B₁/B₂=d₁/d₂, hence r₁/r₂=d₁/d₂. Therefore A.