Chapter 17, Problem 56GP

Static cling You pull your domes from the dryer and find that they stick together you take off your coat and find that your pants sock to your legs. Static cling like this can occur tor two reasons. First, different types of atoms nave greater or lesser affinity for additional electrons. When two different materials are tubbed together, the atoms with a greater electron affinity attract electrons from the material with a lesser electron affinity. Because of this, the substance that gams electrons becomes negatively charged and the substance ma, loses electrons becomes positivity charged. The differently charged materials attract and sick together.

Second static cling can occur between charged and uncharged objects. For instance, you may notice that a sock removed from the dryer is attracted to an uncharged sweater you are wearing. Or sometimes your short sticks to your legs. This happens because the molecules in a charged piece of clothing cause the electric charge inside the molecules of the nearby uncharged objects to slightly redistribute (to become polarized) so that the unlike charge of the molecule moves closer to the charged object and is attracted more than the same molecular charge of the same sign. Which is slightly farmer away (see Figures 17.9b and c).

Some people use fabric softener to prevent static cling. This product coats cloth fibers with a thin layer of electrically conductive molecules, thus preventing buildup of static electricity. you can also use a metal clothes hanger to remove electric charge from already clean charged clothes. Brush the hanger on the inside of the garment of the garment from top to bottom.

Shoes scuffing on different surfaces can also cause electric charge transfer. For that reason, hospital personnel wear special shoes in hospital operating rooms to avoid sparking that might ignite flammable gases in the room.

& EST Shocking your friend (a) You shuffle across the rug and then place your finger near your friend's nose, causing a small spark that transfers about ${10}^{**\#x2212;9}$

C of charge from you to your friend. Determine the number of electrons transferred. (b) Estimate the fraction of electrons in your body that were transferred to the friend. Note that the electron mass is about 1/20,000 the mass of the atom—the nuclei are much more massive—and the mass of an average atom in the body is about $2\times {10}^{-26}$ kg. (Note: Don't get hung up on minutia—this is a rough estimate.)