An electron is travelling along the x-direction. It encounters magnetic field in the y-direction. Its subsequent motion will be

Options

A. straight line along the x direction
B. a circle in the XZ plane
C. a circle in the YZ plane
D. a circle in the XY plane

Answer

D

Explanation

If a particle carrying charge q and moving with velocity v thourght a point in magnetic field experiences a deflecting force F then magneitc field B given by

`f=qvxxB`
here `v=v_(x)hati` and `B=B_(y) hat j`
`therefore F=ewv_(x)b_(y)(hati xx hat j) =ev_(x)B_(y)hatk`
hence susbequent motion of hte charged partocle will be a circle in the XY plane