An electron is made to move from East to West with a speed of `10^(8)` m/s in a uniform magnetic field of `10^(-4)` T. If the direction of the magnetic field is from South to North, calculate the magnitude and direction of the magnetic force on the electron.

Explanation

Given,
`v=10^(8)m//s` towards West = `-10^(8)hati`,
`B=10^(-4)` T towards North = `-10^(-4)hatj`,
`q=e=1.6xx10^(-19)C`
and F = ?
Magnetic force, `F=q(vxxB)`
= `1.6xx10^(-19)(-10^(8)hatixx10^(-4)hatj)`
= `-1.6xx10^(-15)(hatixxhatj)=-1.6xx10^(-15)hatk`
So, `|F|=1.6xx10^(-15)N`
The direction of force will be towards the plane of paper.