Truck with a trailer and a massive electromagnet

Truck with a trailer and the trailer should be filled with an extremely large
electro magnet (2 metres high, 10 metres long and 2,50 metres wide)
               (Or 2 x 2 metres high, 5 metres long and 2,50 metres wide)
-Seeing the range of such an electro magnet
-And seeing how much it can attract

Only putting it on when far away enough from the truck and the hanger
-At a testing ground without people