The ocean is salty because it contains many dissolved ions. as these charged particles move with the water in strong ocean currents, they feel a force from the earth's magnetic field. positive and negative charges are separated until an electric field develops that balances this magnetic force. this field produces measurable potential differ- ences that can be monitored by ocean researchers. the gulf stream moves northward off the east coast of the united states at a speed of up to 3.5 m/s. assume that the current flows at this maximum speed and that the earth's field is 50 ut tipped 60° below horizontal 63. what is the direction of the magnetic force on a singly ion- ized negative chlorine ion moving in this ocean current? a. east b. west c. up d. down 64. what is the magnitude of the force on this ion? a. 2.8 x 10-23 n b. 2.4 x 10-23 n c. 1.6 x 10-23 n d. 1.4 x 10-23 n 65. what magnitude electric field is necessary to exactly balance this magnetic force? a. 1.8 x 104 n/c b. 1.5 x 10-4n/c c. 1.0 x 10 - n/c d. 0.9 x 10 - n/c 66. the electric field produces a potential difference. if you place one electrode 10 m below the surface of the water, you will measure the greatest potential difference if you place the second electrode a. at the surface. b. at a depth of 20 m. c. at the same depth 10 m to the north. d. at the same depth 10 m to the east.