A neutron, a proton , and an electron and an alpha particle enter a region of constant magnetic field with equal velocities . The magnetic field is along the inward normal to the plane of the paper . The tracks of the particles are labelled in fig. the electron follows track .... and the alpha particle follows track.....

Options

A. C,A
B. `A,C
C. C,A
D. B,D

Answer

D

Explanation

(1)For a neutron,`q=0,F=qvB sin theta=0 therefore ` Track C corresponds to neutron. (2) The electron is the only negatively charged particle it is deflected towards right along the track D. (3) Both protons and a particle are positively charged and they deflected towards left. The radius of the circluar track `r=(mv)/(qB) therefore v and B` are constant. `therefore r propto m/q therefore r_alpha propto 4/2 or 2 and r_p propto 1/1 or 1 therefore r_alphagtr_p therefore` Track B corresponds to `alpha` particle and track A corresponds to the proton. `therefore` The track are D and B.