If the initial velocity is zero then it will keep it that way.<br />If the initial velocity is in the same direction of the magnetic field, then the electron will move with constant velocity. <br />The force on the electron in the magnetic field is <img class='tex' src="/demolab/smf/teximages/f/a/a/faab2841ac1cdadebbbaa372041cdc11.png" alt="\vec{F}=q\vec{v}\times\vec{B}" />.<br />If the direction of <img class='tex' src="/demolab/smf/teximages/2/c/5/2c5ce0b78c3e457c0c2e93c5c854371b.png" alt="vec{v}" /> is parallel to direction of <img class='tex' src="/demolab/smf/teximages/3/4/4/3441467fdbb94a7412b8b9cdc3a7aaf3.png" alt="\vec{B}" />, then <img class='tex' src="/demolab/smf/teximages/4/d/e/4de541c7b5d210d73e078d3a58189473.png" alt="vec{F}=0" />.<br />so it will move with constant velocity.<br /><br />If the direction of <img class='tex' src="/demolab/smf/teximages/2/c/5/2c5ce0b78c3e457c0c2e93c5c854371b.png" alt="vec{v}" /> is perpendicular to the magnetic field <img class='tex' src="/demolab/smf/teximages/3/4/4/3441467fdbb94a7412b8b9cdc3a7aaf3.png" alt="\vec{B}" />, then the force is also perpendicular to the velocity, so the force will only&nbsp; change the direction of velocity -- and it is a circular motion.<br /><br />If velocity contain both parallel component and normal component, it will move with helical path.<br /><br />You are welcomed to check out [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=36.0]Charged particle motion in E/B Field[/url].