Moving Charges and Magnetism - Result Question 8
8. The magnetic force acting on a charged particle of charge $-2 \mu C$ in a magnetic field of $2 T$ acting in $y$ direction, when the particle velocity is
$(2 \hat{i}+3 \hat{j}) \times 10^{6} ms^{-1}$, is
[2009]
(a) $4 N$ in $z$ direction
(b) $8 N$ in $y$ direction
(c) $8 N$ in $z$ direction
(d) $8 N$ in $-z$ direction
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Answer:
Correct Answer: 8. (d)
Solution:
- (d) The magnetic force acting on the charged paraticle is given by
$ \begin{aligned} & \overrightarrow{{}F}=q(\overrightarrow{{}v} \times \overrightarrow{{}B}) \\ & .=(-2 \times 10^{-6})[{2 \hat{i}+3 \hat{j}) \times 10^{6}} \times(2 \hat{j})] \\ & =-4(2 \hat{k}) \\ & =-8 \hat{k} \end{aligned} $
$\therefore$ Force is of $8 N$ along negative $z$-axis.
