Understand the bodies having electric charge which linear sizes can be neglected as dot charges. The distance between them can be measured to measure directly by means of a ruler, calipers or a micrometer. But it is practically very difficult to make it. Therefore it is possible use Coulomb's law.
It is required to you
- - sensitive dynamometer;
- - calculator;
- - table of dielectric permeability of substances.
Instruction
1. Attach the known charges to levers of a sensitive dynamometer. Use a tortional dynamometer which measures force depending on turn of a wire on which one of bodies is suspended. At placement of charges avoid from touch, otherwise the size of electric charge will be redistributed, force of interaction will change, and measurement will be not true.
2. At measurement of force of interaction surely consider polarity of charges as the charges of the same name make a start, and heteronymic are attracted. Therefore scales can rotate in different directions. When determining distance between heteronymic charges, prevent their contact.
3. Measure force of interaction of charges in Newtons. To define distance between two charges of r, find the work of modules of sizes of these charges q1 and q2, increase the turned-out number by coefficient 9•10^9, divide result into the module of force measured by F dynamometer. Take the square root r= from the turned-out result √ (9•10^9•q1•q2) / F). Receive result in meters.
4. If interaction of charges is carried out not in a vacuum or air, consider dielectric permeability of the environment where there is an interaction. Find its value in the special thematic table. For example, if charge are in kerosene, then consider that its dielectric permeability ε=2. The dielectric permeability of a vacuum and air is equal ε=2.
5. When calculating distance between charges which are in substance which dielectric permeability differs from 1 before extraction of a square root divide result of calculation for distance between two charges into dielectric permeability ε. In this case the formula for calculation of distance between two dot charges will take r= form √ (9•10^9•q1•q2) / ε\• F).