
let angle of deviation is a.
from figure, sina $=\mathrm{d} / \mathrm{R}$
where, $\mathrm{d}=3 \mathrm{mv} / 5 \mathrm{qb}$ and we know radius of circular path attained by charged particle $, \mathrm{R}=\mathrm{mv} / \mathrm{qb}$
now, sina $=(3 m v / 5 q b) /(m v / q b)=3 / 5=\sin 37^{\circ}$
$\Rightarrow a=37^{\circ}$
we know, angle of deviation = emergent angle - incidence angle
$=\theta+53^{\circ}$
or, $37^{\circ}=\theta+53^{\circ}$
or, $\theta=90^{\circ}$
Statement $-2$ : The magnetic field due to finite length of a straight current carrying wire is symmetric about the wire.
$1^{st}$ Way : By using spring of smaller torsion constant.
$2^{nd}$ Way : By using a smaller coil
$3^{rd}$ Way : By using a stronger magnet
$4^{th}$ Way : By using a coil having fewer number of turns.