Aim: How do we explain electric charge?

Do Now: 1) What is an atom? The smallest particle of a particular substance or element. 2) What particles does an atom consist of? Protons, Neutrons, Electrons

Example of Atoms below: What are the charged parts of the atom Example of Atoms below: What are the charged parts of the atom? Protons and Electrons

Charging by Friction When certain objects are rubbed together, they acquire electric charge. Examples: Rubber and Fur- Electrons will move from the fur to the rubber rod. The fur becomes positively charged and the rubber rod becomes negatively charged. Glass and silk- Electrons will move from the glass to the silk. The silk becomes negatively charged and the glass rod becomes positively charged.

Charging by Friction

Why are objects charged the way that they are? Match each of the following objects with the descriptions below: Uncharged C Positively Charged A Negatively Charged B a) Possesses more protons than electrons b) Possesses more electrons than protons c) Equal numbers of protons and electrons

Measuring Charge Protons and electrons are elementary charges. We can measure electric charge using elementary charges or coulombs. 1 elementary charge = 1.6 x 10-19 C 1 C = 6.25 x 1018 elementary charges

Charge Conversion Examples How many coulombs is 4 protons? How many coulombs is 2 electrons? 1 proton=+1.6 x 10-19 C 1 electron=-1.6 x0 10-19 C 1.6 x 10-19 C (4)=+6.4 x 10-19 C -1.6 x 10-19 C (2)=-3.2 x 10-19 C

More Charge Problems 1. TRUE or FALSE: An object that is positively charged contains all protons and no electrons. 2. TRUE or FALSE: An object that is negatively charged could contain only electrons with no accompanying protons. 3. TRUE or FALSE: An object that is electrically neutral contains only neutrons.

4. Identify the following particles as being charged or uncharged 4. Identify the following particles as being charged or uncharged. If charged, indicate whether they are charged positively or negatively. (n = neutron, p = proton, e = electron) Particle A Charge=-1 Particle B Charge=0 Particle C Charge =+2

5. Determine the quantity and type of charge on an object that has 3 5. Determine the quantity and type of charge on an object that has 3.62 x 1012 more protons than electrons. 3.62 x 1012(1.6 x 10-19)=5.8 x 10-7 C 6. After some rather exhausting counting (and a rather tall tale), a physics teacher determines that a very small sample of an object contains 8.25749 x 1017 protons and 5.26 x 1014 electrons; the charge on this object is ____ Coulombs. (8.25749 x 1017 – 5.26 x 1014)(1.6 x 10-19 )=0.132 C 7. The amount of charge carried by a lightning bolt is estimated at -10 Coulombs. What quantity of excess electrons is carried by the lightning bolt? -10 C/(1.6 x 10-19 C)=6.25 x 1019 C

Charged Interactions Electrostatic Force -Opposite charges attract -Like charges repel