1.2.1 Preparing a "U" tape Use a strip of tape about 20 cm or 8 inches long (about as long as this paper is wide). Shorter pieces are not flexible enough, and longer pieces are difficult to handle. Fold over one end of the strip to make a non-sticky handle: handle 1: INTERACTIONS OF ELECTRIC CHARGES 3 Prepare a U tape as follows: . Stick a strip of tape with a handle down onto a smooth flat surface such as a desk. . Smooth this base tape down with your thumb or fingertips. This base tape Upper tape provides a standard surface to work from. (Without this base tape, you get Base tape different effects on different kinds of surfaces.) Stick another tape with a handle down on top of the base tape. . Smooth the upper tape down well with your thumb or fingertips. Pull rapidly . Write U (for Upper) on the handle of the upper tape. . With a very quick motion, pull the U tape up and off the base tape, leaving the base tape stuck to the desk. Your hand and a U tape O Hang the U tape vertically from the edge of the desk, and bring your hand near the hanging tape. In the box provided, write a brief description of what happens: Does it matter which side of the tape you approach? . . . . . . 1.2.1b If the tape is in good condition and the room is not too humid, you should find that there is an attraction between the hanging strip and your hand when you get close to either side of the tape. If you don't see an attraction, re-make the tape. You can re-use the same piece of tape by again sticking it down on the base tape and then pulling it off, as follows: Standard procedure for making a U tape STANDARD PROCEDURE FOR MAKING OR REMAKING A U TAPE * Run your finger along the base tape that is on the desk. . Stick the U tape down on the base tape, smoothing the tape down well. . Jerk the U tape very quickly off the base tape. . Test to make sure that the tape is attracted to your hand."