Acceleration of electron?? Please atleast help me by explaining what I should do. I have found velocity by setting kenetic energy to .5mv^2 and used the mass of an electron for the mass and found that velocity is 6.182. Next i set mass x gravity=qvbsin(theta) and apparently whatever i did from here is wrong. Thanks for your help. The electrons in the beam of a television tube have a kinetic energy of 2.10 10-15 J. Initially, the electrons move horizontally from west to east. The vertical component of the earth's magnetic field points down, toward the surface of the earth, and has a magnitude of 1.00 10-5 T. What is the acceleration of an electron in part (a)?