Electrostatics Ali Munn and Paige Dreger PHYS 122 Sec L03 Purpose : The intention of this experiment was to investigate some aspects of electric charge and to calculate a value for q, which is the charge on a pith ball. Introduction : In the mid 1700's, Benjamin Franklin suggested that charges be designated positive and negative. The two types of charges are categorized as positive or negative. Like charges repel each other, while opposites attract each other. Most atoms are neutral, therefore most objects are neutral. Electrons are negative and can move from one object to another, unlike positive electrons which are fixed. A charged object can either have a surplus of electrons and be negatively charged, or deficit electrons and be positively charged. Finally, conductors allow electrons to freely, while insulators do not. In the lab we investigated these properties. Coulomb's law can be stated as: Where F is the force, k is the Coulomb’s constant, Q1 and Q2 are the charges and d^2 is the distance between the forces. Procedure : The PVC rod was rubbed and the charged end was slowly lowered into the can without touching the sides and a charge of -44 was recorded. This was repeated with the nylon rod and a charge of 72 was recorded. The number of excess or deficit electrons on both strips was also recorded at 2.75x10^11 electrons and 1.10x10^10 electrons, respectively.
Then a pith ball was charged up and lowered into the can ¼, ½, ¾ and almost all the way down. The charges were recorded respectively at -9.9 e, -10 e, -10.1 e and -10.3