QUESTION 3 The figure below shows a top view of a bar that can slide on two frictionless rails. The resistance is R and a uniform magnetic field is directed perpendicularly downward, into the page as shown. When the bar is moved to the right with a constant velocity, which end of the resistor R is positive? a or b? a Bin R F app b O A Bóth points are at the same potential OB. Point a is at the higher potential O C. Point b is at the higher potential xx x x X x x X xx Xx * x x x x x x x x × x x x x x x x * x x x X x

QUESTION 3 The figure below shows a top view of a bar that can slide on two frictionless rails. The resistance is R and a uniform magnetic field is directed perpendicularly downward, into the page as shown. When the bar is moved to the right with a constant velocity, which end of the resistor R is positive? a or b? a Bin R F app b O A Bóth points are at the same potential OB. Point a is at the higher potential O C. Point b is at the higher potential xx x x X x x X xx Xx * x x x x x x x x × x x x x x x x * x x x X x