Uniform magnetic and electric fields exist between the two o…

Uniform magnetic and electric fields exist between the two oppositely charged parallel plates shown in the figure above. An electron travels horizontally between the plates. Assuming gravitational effects to be negligible, which of the following diagrams shows a combination of electric and magnetic field directions that will allow the electron to travel undeflected?

A charge of magnitude 2 nC is placed at the origin. An ident…

A charge of magnitude 2 nC is placed at the origin. An identical charge is placed 2 millimeters from the origin on the x axis, and a third identical charge is placed 2 millimeters from the origin on the y axis. What is the magnitude of the force on the charge at the origin?