An electron moves in a straight line at speed 250 m/s along the positive y-axis through uniform electric and magnetic fields. The magnetic field is directed into the page and has magnitude 2 T. Neglect gravity. The mass of the electron is 9.1 x 10-³1 kg. a. What is the electric field (specify both magnitude and direction)? b. Now imagine the electric field has been turned off. What will be the radius of the electron's subsequent path?

An electron moves in a straight line at speed 250 m/s along the positive y-axis through uniform electric and magnetic fields. The magnetic field is directed into the page and has magnitude 2 T. Neglect gravity. The mass of the electron is 9.1 x 10-³1 kg. a. What is the electric field (specify both magnitude and direction)? b. Now imagine the electric field has been turned off. What will be the radius of the electron's subsequent path?