Question

A positive charge particle enters and comes out from a uniform magnetic field which exists with direction inside the paper in a finite space of width $120cm$ as shown in the figure. Find the radius of the circular path of charge particle (in meter) when it is inside the magnetic field.

Answer 1

Answer: 4

Let $R$ is the radius of the circular path of the charged particle in uniform magnetic field.
From the diagram, the width of the magnetic field region will be
$d=R\cos 37^{\circ }-R\cos 60^{\circ }$
$\Rightarrow 120\times 10^{-2}=R\times \frac{4}{5}-R\times \frac{1}{2}$
$\Rightarrow \frac{3R}{10}=1.2$
$\Rightarrow R=4m$
$R=4m$