Answer Happy

Tear up a piece of paper into many small (< 1 cm across) pieces and place them on the table. Charge up an inflated balloon by rubbing it on a wool sweater or other cloth good for generating static electricity. Hold the balloon over the pieces of paper and lower until the electric attraction picks up the pieces of paper and pulls them to the surface of the balloon. If this does not happen, try again to charge the balloon. Try rubbing it on different types of cloth until you find one that is good for producing a charge on the balloon. 1. You charged the balloon, but not the pieces of paper. Why does the balloon attract the pieces of paper even though they are neutral? 2. When the pieces of paper reach the surface of the balloon some will stick and some will fall off. What is the cause of this behavior?
Hang the two balloons next to each other using lengths of string at least one foot long (longer is better). Hang them so that the distance between them is no more than a few centimeters apart (closer is better). Measure the length of the strings. Charge up both balloons. If they are charged, they should repel each other so that they are no longer hanging vertically. Measure the angle at which the strings are hanging, relative to the vertical axis. You can measure this angle using a protractor or a phone app (such as Angle Meter) that measures orientation. 3. Using the measurements you've made, estimate the charge on the balloons. What is your estimate for the charge? (Hint: Assume that the balloons are point-charges. Draw a free- body diagram for one of the balloons. Apply Newton's 2nd law. Use the fact that the balloons are static to eliminate the unknown tension and solve for the electric force. Then use Coulomb's law to determine the electric charge, assuming that the two balloons have the same charge.) Derive an equation that finds the charge in terms of the parameters and constants. Show your derivation. Then, calculate the amount of charge on each balloon. 30 l = 75 cm d = 6 cm 0 = 22° m = 2.2 g
Make sure that two inflated balloons are neutral. You can do this by touching them to a large conducting object (such as a metal chair) or a conducting object that is in contact with the ground (such as a faucet, which are usually connected to the ground through metallic plumbing). They should hang vertically when they are neutral. Draw an arrow on the top of each balloon pointing toward the point on the balloon that is facing the other balloon. 2 Now charge up only that part of the balloon that faces the other balloon (the part of the balloon your arrow is pointing toward). Do this by rubbing the balloons on cloth taking care to rub only that small area of the balloon that your arrow is pointing toward. Observe the hanging balloons after you have charged them in this way. 4. We observe that the hanging balloons tend to rotate such that the parts that you charged move farther away from each other? Based on this observation, does the charge remain confined to the small area that you rubbed, or does it migrate around the balloon and become evenly distributed? Why does this happen?