Chapter 28, Problem 42AP

(a) A proton moving with velocity $\stackrel{\to }{v}={\nu }_i\hat{i}$ experiences a magnetic force $\stackrel{\to }{F}=F_i\hat{j}$. Explain what you can and cannot infer about $\stackrel{\to }{B}$ from this information. (b) What If? In terms of F_i, what would be the force on a proton in the same field moving with velocity $\stackrel{\to }{v}=-{\nu }_i\hat{i}$? (c) What would be the force on an electron in the same field moving with velocity $\stackrel{\to }{v}=-{\nu }_i\hat{i}$?