Question

Two chained particles traverse identical helical paths in a completely opposite sense in a uniform magnetic field $\bar{B}=B_0\hat{K}$

• A. They have equal z-components of momenta
• B. They must have equal charges
• C. They necessarily represent a partical-antipar ticle pair
• D. The charge to mass ratio satisfy : $(e/m)_1+(e/m)_2=0$

Answer 1

Answer: (D)

The charge to mass ratio satisfy : $(e/m)_1+(e/m)_2=0$

Answer 2

Since the charged particles traverse identical helical paths in a completely opposite sense in a uniform , magnetic field B, their radii(r = mv sin $\theta$ /eB) and frequencies (v = eB/ 2 $\pi m$) must be equal for this $(e/m)_1=-(e/m)_2 or (e /m)_1 +(e /m)_2=0$