Chapter 7.1 – Static Charge

Review: Atom:

o __________________ (-)o __________________ (+)o __________________ (0)

Ions:o Lose electrons = ____________________ iono Gain electrons = ____________________ ion

Static Charge: Static charge (or static electricity) refers to ______________________________ that can

be collected and held in one place In any solid material, the ________________________ of the atoms is able to vibrate,

but can not move. Only ________________________ are able to move around. This means that:

o All solid materials are charged by the transfer of electrons. If an electron is taken away from a neutral atom, the atom will then have a

______________________ charge. If an electron is added to a neutral atom, the atoms will then have a

_______________________ charge. The movement, or transfer, of electrons from one place to another changes the charge

on an atom.

Friction and Electron Transfer: _________________________ occurs when objects rub against each other Friction causes one object to lose electrons and the other to gain electrons For example:

o _______________ is a type of plastic used in film and overhead transparencies. If acetate is rubbed with paper towel, _________________________ move from the paper towel onto the acetate.

o In A, the paper towel and the acetate are both neutral (equal numbers of + and – charges).

o In B, after the paper towel and acetate have been rubbed together, the acetate has more - charges and the paper towel has more + charges.

Insulators and Conductors:

_______________________________ = materials that do not allow charges to move easilyo Ex. glass, rubber, rocks, ceramics, wood

_______________________________ = materials that allow electrons to travel freelyo Ex. metals, water, people

A plastic rod is a good example of an insulator. If you rubbed only one end of the plastic with a paper towel, only that end of the plastic rod

would become ______________________. The charges cannot move through the insulator.

Metals allow charges to flow through them. If you rubbed only one end of a metal rod with the paper towel, the entire metal rod would

become charged. Metals are very good conductors because the atoms in a metal always have at least one

electrons that can be easily moved.

Coulombs:Electrical

charges are measured in ________________________ (C), named after the French physicist Charles Augustin de Coulomb.

It takes _________________________ electrons to produce 1 C of charge. A typical lightning bolt can carry ______________________ of charge.

Generating Static Charge: There are many examples of using ___________________ in nature to produce static

electricity. For example:o The friction between moving air particles in storm clouds produces static charge,

which can then travel to Earth as ____________________________.o A ___________________________ generator uses friction to generate a charge

on a metal dome. A moving belt produces a static charge at the base of the generator, which then collects on the dome.

Applications of Static Charge: Although static electricity is often unwanted (hence the reason most of us use

__________________________ in the laundry), it can be useful. For example:o Static electricity makes ____________________________ “sticky”.o Devices in _________________________ collect particles that would normally

flow out into the air.o When painting cars, the ________________ is given an electrical charge so that

it sticks to the metal of the car and nowhere else.

Dangers of Static Charge: Sometimes static charge can be _______________________________.

Trucks that deliver fuel must have a special cable that allows any static charge to flow into the _____________________-. This prevents any sparks that could cause the fuel to explode.

Allowing charge to flow into the Earth is called ______________________. The Earth is so big that it can accept a lot of charge without becoming charged itself.

To protect a building from lightning, a ________________________________ is placed on top of the building. If lightning occurs near the building, the charge will pass through the rod to the ground, rather than into the building.

Chapter 7.2 – Electric Force

Force: Force is defined as a push or a pull. There are two different types of forces:

o _______________________ forces, which are forces that can have an effect only on objects they touch.

o ___________________________ forces, apply force to an object without touching it. Ex. ___________________________

Electric Force: _________________________________ = push or a

pull between charged objects.

The Laws of Static Charge: Like charges ___________________________ Opposite charges ____________________________ _________________________ objects are attracted to

charged objects. If you increase the _________________________________________, the attraction or

repulsion between charges will be greater. If you decrease the _________________________ between charges, the amount of

attraction or repulsion will be greater.

We can create charge in two ways: Charging by _______________________

o Charging a __________________ object by __________________ it to a charged object

o Touching the neutral object with a charged object allows ____________________ to be transferred to the neutral object.

Charging by _______________________o Charging a ___________________ object by

bringing a charged object ___________ ito No ______________________ are being

transferred instead, inducing a charge repositions electrons inside the neutral object

o As soon as the charged object is moved away, the neutral object goes back to the way it was before the charged object was brought close.

Attraction of Neutral Objects: _____________________ explains why neutral objects are

attracted to charged objects. For example, when you rub a balloon against your hair, it

becomes ________________________________________. It will still stick to a ____________________ wall because a positive charge is induced on the surface of the wall as it repels the negative charges away.