Charge

Warm Up

• What is an electron? Where is located in an atom?

• What is a proton? Where is it located in an atom?

Atoms

• What are the parts in an Atom?

Electrons

• Electrons are present in the region of space outside the nucleus.

• They are negatively charged and weakly bound to the atom.

• They are loosey goosey and float from one atom to the next

• They like to party

Protons and Neutrons

• The nucleus of the atom contains positively charged protons and neutral neutrons.

• They are in the center of the atom.

• The protons and neutrons will remain within the nucleus of the atom.

• They like to stay at home and watch Netflix.

• THEY NEVER LEAVE THEIR HOME

Charges at Rest

Charge• there are two kinds of charge, positive and

negative• positive charge comes from having more

protons than electrons• negative charge comes from having more

electrons than protons

Charge Interactions

• Opposite charges repel

• Same charges attract

Opposites Attract

Sames Repel

• “Why do you look at the speck of sawdust in your brother’s eye and pay no attention to the plank in your own eye?”

Electrostatic charging

• Materials are divided into three categories, depending on how easily they will allow charge (i.e., electrons) to flow along them. These are:– conductors – insulators– semi-conductors

Conductors

• the outermost electrons in the atoms are so loosely bound to their atoms that they’re free to travel around. metals, for example

Insulators

• In insulators, on the other hand, the electrons are much more tightly bound to the atoms, and are not free to flow, rubber, wood, plastic for example

Semi-Conductors -

• In between conductor and insulator• silicon is a good example

Three ways that objects can be given a net charge

• Charging by friction

• Charging by conduction

• Charging by induction

Friction

• this is useful for charging insulators. • rub one material with another • Electrons transfer from one material to the

other.• For example, rubbing glass with silk or saran

wrap generally leaves the glass with a positive charge; rubbing PVC rod with fur generally gives the rod a negative charge.

Charge by Friction

• http://phet.colorado.edu/en/simulation/balloons

Conduction

• useful for charging metals and other conductors.

• If a charged object touches a conductor• charging the conductor with the same sign as

the charge on the object

Induction

• also useful for conductors. • a charged object is brought close to the conductor, and

does not touch it. • If the conductor is connected to ground (ground is

basically anything neutral that can give up electrons to, or take electrons from, an object),

• electrons will either flow on to it or away from it. • When the ground connection is removed , the

conductor will have a charge opposite in sign to that of the charged object

Polarization

• is the process of separating opposite charges within an object