Q.
The figure shows three situations when an electron with velocity v travels through a uniform magnetic field B. In each case, what is the direction of magnetic force on the electron?
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 respectively. In figure (3) velocity of electron and direction of magnetic field are antiparallel, so no force will act on electron.