An α -particle (mass 4 amu) and a singly charged Sulphur ion (mass 32 amu) are initially at rest. They…

An α-particle (mass 4 amu) and a singly charged Sulphur ion (mass 32 amu) are initially at rest. They are accelerated through a potential V and then allowed to pass into a region of uniform magnetic field which is normal to the velocities of the particles. Within this region, the α-particle and the sulphur ion move in circular orbits of radii Rα and RS, respectively. The ratio RSRα is __________ .

Solution

When a particle moves on a circular path in a magnetic field then,

R=mvqB=2mEqB=2mqVqB=2mVqB

According to given data,

V=constant& B=constant

Rmq

RαRS=mαqα×qSmS=42×132

RαRS=116=14

Then, RSRα=4

!

Asked in: JEE Advanced 2021 (Paper 1)

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