Chapter 13 Static Electricity

1 Electrostatics At the end of the lesson, I can… 1. STATE that there are positive and negative charges, and that charge is measured in coulombs 2. STATE that unlike charges attract and like charges repel 3. DESCRIBE an electric field as a region in which an electric charge experiences a force 4. DRAW the electric field of an isolated point charge and recall that the direction of the field lines gives the direction of the force acting on a positive test charge 5. DRAW the electric field pattern between two isolated point charges 6. SHOW understanding that electrostatic charging by rubbing involves a transfer of electrons 7. DESCRIBE experiments to show electrostatic charging by induction 8. DESCRIBE examples where electrostatic charging may be a potential hazard 9. DESCRIBE the use of electrostatic charging in an electrostatic precipitator, and apply the use of electrostatic charging to new situations 10. STATE that unlike charges attract and like charges repel 11. DESCRIBE an electric field as a region in which an electric charge experiences a force CHAPER 13 Static Electricity

2 Electrostatics 1.1 All matter consists of atoms. Atoms contain three types of smaller particles: electrons, protons and neutrons. Of these three, both the protons and electrons are charged. 1.2 Protons are positively charged and electrons are negatively charged. 1.3 Generally, an atom has a neutral charge as it has equal amount of positive and negative charges. When it loses electron(s), it becomes positively charged and when the atom gains electron(s), it becomes negatively charged. 1.4 Charged atoms are called ions and ions in matter can’t move freely. 1.5 Charges are measured in coulombs (C). 1.6 Like charges repel and unlike charges attract. d 2.1 When insulating materials rub against each other, they may become electrically charged. The material that attracts electrons weakly will loose electrons and becomes positively charged. 2.2 Rubbing doesn’t create charges, it transfers charges. 2.3 When a glass rod is rubbed against a piece of silk, the friction between them causes electrons to gain energy. Electrons from the glass rod gain enough energy to leave the atoms and transferred onto the silk. 1. Electrical Charges 2. Charging By Friction Electrostatic effect of water

3 Electrostatics 2.4 Both the glass and the silk are insulating materials. Insulators prevent the electrons from moving and so the charges remain static. 3.1 Conductors cannot be charged by friction because electrons can be transferred between them once they are in contact. 3.2 Induction is charging an electrical conductor without any contact between the conductor and the charging body. 3.3 Charging Two Conductors with Equal and Opposite Charges 3. Charging Conductors By Induction

4 Electrostatics 3.4 Charging A Conductor by Earthing. Earthing is the process of removing excess cha