B. Fig B. Fit the cotton reel between the cardboard pieces. To do this, straighten out a paper clip and push it through the holes in the cardboard and through the centre of the cotton reel. Bend down the paper clip ends to secure the cotton reel. Fig C Make a handle by attaching a bent paper clip to the end of the pencil with tape, as shown in Fig. D Make two holes in the cardboard box and then push the pencil through these two holes, as shown in Fig.
E Tie one end of the string around the electromagnet.
Lay the string over the cotton reel and tie the free end to the pencil. By turning the pencil, the electromagnet should move up and down Fig. F Now, connect the free ends of the electromagnet through a switch to the battery. Your crane is ready for use. To use the crane, put some very small pieces of iron below the electromagnet.