A beam of electrons is sent horizontally down the axis of a tube to strike a fluorescent screen at the end of the tube. On the way, the electrons encounter a magnetic field directed vertically downward. The spot on the screen will therefore be deflected: O upward Odownward to the right as seen from the electron source to the left as seen from the electron source O not at all

A beam of electrons is sent horizontally down the axis of a tube to strike a fluorescent screen at the end of the tube. On the way, the electrons encounter a magnetic field directed vertically downward. The spot on the screen will therefore be deflected: O upward Odownward to the right as seen from the electron source to the left as seen from the electron source O not at all