Question

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

Answer 1

$r=\frac{m v}{q B}=\frac{\sqrt{2 k m}}{q B}, m=\frac{r^2 q^2 B^2}{2 k}$

$m =\frac{\frac{1}{100} \times \frac{3}{100} \times 2 \times 2 \times 4 \times 10^{-3} \times 4 \times 10^{-3} \times 10^{-12}}{2 \times(100) \times 10^{-6}}$
$=144 \times 10^{-18} kg$