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4.Moving Charges and Magnetism
medium
Mixed $H{e^ + }$ and ${O^{2 + }}$ ions (mass of $H{e^ + } = 4\,\,amu$ and that of ${O^{2 + }} = 16\,\,amu)$ beam passes a region of constant perpendicular magnetic field. If kinetic energy of all the ions is same then
A
$H{e^ + }$ ions will be deflected more than those of ${O^{2 + }}$
B
$H{e^ + }$ ions will be deflected less than those of ${O^{2 + }}$
C
All the ions will be deflected equally
D
No ions will be deflected
Solution
(c) $r = \frac{{\sqrt {2mK} }}{{qB}} \Rightarrow r\; \propto \;\frac{{\sqrt m }}{q} \Rightarrow \frac{{{r_{H{e^ + }}}}}{{{r_{{O^{ + + }}}}}} = \sqrt {\frac{{{m_{H{e^ + }}}}}{{{m_{{O^{ + + }}}}}}} \times \frac{{{q_{{O^{ + + }}}}}}{{{q_{H{e^ + }}}}}$
$ = \sqrt {\frac{4}{{16}}} \times \frac{2}{1} = \frac{1}{1}.$ Then will deflect equally.
Standard 12
Physics