Question 190: Magnetism and Matter

Question

The figure shows a region of length ‘l’ with a
uniform magnetic field of 0.3 T in it and a
proton entering the region with velocity 4 $$ 	imes $$ 10
5
ms
–1
making an angle 60
o
with the field. If the
proton completes 10 revolution by the time it
cross the region shown, ‘l’ is close to
(mass of
proton = 1.67 $$ 	imes $$ 10
–27
kg, charge of the proton =
1.6 $$ 	imes $$ 10
–19
C)

Accepted Answer

$$l$$ = 10 ÃÂ pitch
= 10 $$ 	imes $$ vcos60
o
$$ 	imes $$ $${{2\pi m} \over {qB}}$$
= 10 $$ 	imes $$ v $$ 	imes $$ $${1 \over 2}$$ $$ 	imes $$ $${{2\pi m} \over {qB}}$$
= $${{10 	imes 4 	imes {{10}^5} 	imes 3.14 	imes 1.67 	imes {{10}^{ - 27}}} \over {1.6 	imes {{10}^{ - 19}} 	imes 0.3}}$$
= 0.44 m

Answer

0.22 m

Answer

0.11 m

Answer

0.88 m

Answer

0.44 m

Magnetism and Matter

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