An electron has initial velocity and a constant acceleration of in a region in which uniform electric and magnetic fields are present. If , we have to find the electric field .

Solution:             Click For PDF Version

Lorentz force on an electron moving with velocity in electric field and magnetic field is

where,

charge of electron, ,

mass of electron, ,

velocity of electron, ,

and magnetic field , .

Electron in the uniform electric and magnetic fields is moving with acceleration

Therefore, force on the electron will be

From the Lorentz force equation, we write

Or