Several electrons move at speed 6.90 x 105 m/s in a uniform magnetic field with magnitude B= 0.720 T directed downward. Find the magnetic force on the electron at point c. Enter a positive value if the direction of magnetic force is out of the page and enter a negative value if the direction of magnetic force is in to the page. 20.0 20,0 MO -3.9744E- N 30.0