A proton is moving along the positive x-axis in a uniform magnetic field directed along the positive

Question

A proton is moving along the positive x-axis in a uniform magnetic field directed along the positive y-axis. In which direction will the magnetic force act on the proton?

Professor PC Thomas Classes · Answer

Force $\vec{F} = e(\vec{v} 	imes \vec{B}) = e(v\hat{i} 	imes B\hat{j}) = evB\hat{k}$. The force is in the positive z-direction.