Physics - Magnetism Question with Solution | TestHub

PhysicsMagnetismMotion analysis in electric & magnetic fieldMedium2 minQB

PhysicsMediumsingle choice

A proton, an electron, and a Helium nucleus, have the same energy. They are in circular orbits in a plane due to magnetic field perpendicular to the plane. Let $r_{p}, r_{e}$ and $r_{H e}$ be their respective radii, then,

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Answer:

Solution:

We know, $r = \frac{m v}{q B} (∵ K.E.= \frac{1}{2} m v^{2})$
$= \frac{\sqrt{2 m K . E .}}{q B}$
$∴$ K.E. is same for all particle and magnetic field B is also some.
$r \propto \frac{\sqrt{m}}{q}$
For proton: $r_{p} \propto \frac{\sqrt{m_{p}}}{e}$
For electron: $r_{e} \propto \frac{\sqrt{m_{e}}}{e}$
For Helium nuclei: $r_{H e} \propto \frac{\sqrt{4 m_{p}}}{2 e} = \frac{\sqrt{m_{p}}}{e}$

Stream:JEESubject:PhysicsTopic:MagnetismSubtopic:Motion analysis in electric & magnetic field

⏱ 2mℹ️ Source: QB

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