Q. The figure shows three situations when an electron with velocity $\mathbf{v}$ travels through a uniform magnetic field $\mathbf{B}.$ In each case, what is the direction of magnetic force on the electron?
A) $+ \ ve\ z - axis,\ - ve\ x - axis,\ + ve\ y - axis$
B) $- \ ve\ z - axis,\ - ve\ x - axis\ and\ zero$
C) $+ \ ve\ z - axis,\ + ve\ y - axis\ and\ zero$
D) $- \ ve\ z - axis,\ + ve\ y - axis\ and\ zero$
Explanation
(b) According to Fleming’s left hand rule, in figures (1) and (2) magnetic force on the electron will be directed in $–ve\ z - axis$ and $–ve\ x - axis\ $respecively. In figure (3) velocity of electron and direction of magnetic field are antiparallel so, no force will act on electron.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.