3. Un alambre conductor de 30 cm de largo se encuentra de manera perpendicular con un campo de inducción magnética de 0.8 T. Si la fuerza que actúa sobre el alambre conductor es de 1.2 N, indique el valor de la corriente que circula por el alambre.

The magnets are probably damaged or there not strong enough to attached to the refrigerator

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j