Which of the follwing particles will have minimum frequency of revolution when projected with the same velocity perpendicular to a magnetic field?

Options

A. Electron
B. `He^(+)`
C. `Li^(+)`
D. proton

Answer

C

Explanation

A charge particle describes a circular path in atranservse magnetic field. `(mv^(2))/r=qvB therefore v=(qBr)/m and T =(2pir)/v therefore v=1/T =v/(2pir)=(qBr)/m xx 1/(2pir)=(qB)/(2pim)` Proton, electron, ` Li^(+) and He^(+)` have the same charge in magnitude. Similarly same B is used for all as q and B are the same, `vpropto 1/m`. Out of the four particle, litium has the highest mass. hence it will have minimum frequency.