Two conducting pendulums of identical dimensions and material are released from rest from the same initial angle to swing through a region of uniform magnetic field directed into the page. Pendulum 1 consists of a solid copper plate, whereas Pendulum 2 has several narrow vertical slots cut into the plate. It is observed that Pendulum 1 rapidly damps and stops after entering the field, while Pendulum 2 continues to swing back and forth freely for a much longer time. Which of the following best explains this observation?