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4.Moving Charges and Magnetism
medium
A long solenoid has $100\,turns/m$ and carries current $i.$ An electron moves with in the solenoid in a circle of radius $2·30\,cm$ perpendicular to the solenoid axis. The speed of the electron is $0·046\,c$ ($c =$ speed of light). Find the current $i$ in the solenoid (approximate).....$A$
A
$3$
B
$30$
C
$300$
D
$0.3$
Solution
$r = \frac{{mv}}{{qB}} = \frac{{mv}}{{q\left( {{\mu _0}ni} \right)}} \Rightarrow i = \frac{{mv}}{{q{\mu _0}nr}}$
$ = \frac{{91 \times {{10}^{ – 31}} \times 046 \times 3 \times {{10}^8}}}{{16 \times {{10}^{ – 19}} \times 4\pi \times {{10}^{ – 7}} \times 100 \times 23 \times {{10}^{ – 2}}}}$
Standard 12
Physics
