Question 290: Magnetism and Matter

Question

A charge particle of $$2 ~\mu \mathrm{C}$$ accelerated by a potential difference of $$100 \mathrm{~V}$$ enters a region of uniform magnetic field of magnitude $$4 ~\mathrm{mT}$$ at right angle to the direction of field. The charge particle completes semicircle of radius $$3 \mathrm{~cm}$$ inside magnetic field. The mass of the charge particle is __________ $$	imes 10^{-18} \mathrm{~kg}$$

Accepted Answer

$ r=\frac{m v}{q B}=\frac{\sqrt{2 k m}}{q B}, $
$m=\frac{r^2 q^2 B^2}{2 k}$
$$
\begin{aligned}
\mathrm{m}= & \frac{\frac{1}{100} 	imes \frac{3}{100} 	imes 2 	imes 2 	imes 4 	imes 10^{-3} 	imes 4 	imes 10^{-3} 	imes 10^{-12}}{2 	imes(100) 	imes 10^{-6}} \\
& =144 	imes 10^{-18} \mathrm{~kg}
\end{aligned}
$$

Magnetism and Matter

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