Question

Two charged particles traverse identical helical paths in a completely opposite sense in a uniform magnetic field `vec(B)=B_(0)hat(K)`
A. They have equal z-components of momenta
B. They must have equal charges
C. They necessarily represent a particle-antiparticle pair
D. The charge to mass ratio satisfy:
`(e/m)_1+(e/m)_2=0`

Answer 1

Correct Answer - D
In a uniform magnetic field, the two charged particles will traverse identical helical paths in a completely opposite sense if the charge/mass ratio of these two particles is same and charges on them are of opposite character. In this situation `(e//m)_1+(e//m)_2=0`, holds good.