A neutron, a proton, an electron and an `alpha`- particle enter a region of uniform magnetic field with the same velocities. The magnetic field is perpendicular and directed into the plane of the paper. The tracks of the particles are labelled in the figure. The electron follows the track

Options

A. A
B. B
C. C
D. D

Answer

D

Explanation

Aneutron is electrically neutral particles .It will pass undeflected , therefore it follows track C.
Electron is nagatively charge particles
According to fleming.s left hand rule , the magnetic force on the electron will be toward right .Therefore it , follows track D.Proton and alpha partiles are positively charge particles in according with fleming .s hand rule magnetic force on these particles will be toward left Among the track A and B one is of proton and other of `alpha`- particles.
As `r=(mv)/(bq)`
`:. (r_(alpha))/(r_(p))=(m_(alpha))/(m_(p))xx(q_(p))/(q_(alpha))=((4)/(I))((1)/(2))=2`
`r_(alpha)>r_(p)`
Therefore `alpha`- particles follow track B and porton follow track A.