Electric Charge – Chapter 16 Section 1

Where do you see electricity around you?

What is an Electric Charge?

How does something become electrically charged?

Electric Charge – Test your knowledge

There are 2 kinds of electric charge: positive (+) and negative (–)

• Carrier of positive charge in an atom is _______

• Carrier of negative charge in an atom is _______

Proton

Electron

•

Opposite Charges _______ Like Charges _______Attract Repel

How does hair and a balloon become electrically charged?

Understanding how Charges Transfer

• When electrons in an atom are balanced by an equal number of protons and electrons, the atom has what kind of charge?___________________No Net Charge - Neutral

• If an electron is transferred from one neutral atom to another, the second atom gains what kind of charge?__________Negative

• The first atom loses a__________ charge, so the first atom would become _______ charge.

Negative

Atom #1 Atom #2

Positive

• Atoms that are positively or negatively charged are called__________ions

• What is an Electric Charge? Physical sate of an object or matter with an absence or excess of electrons.

• What is static electricty? The buildup of an electric charge, either positive or negative, on

a material’s surface

Particle Charge ( C ) Mass (Kg)electron (charge = –e) -1.60x10-19 9.109x10-31

protons (charge = +e) 1.60x10-19 1.673x10-27

Neutron 0 1.675x10-27

Charge and Mass of Atomic Particles

When an object is charged, its charge is always a multiple of a fundamental unit of charge, symbolized by the unit e.

So an object can have a charge of +/-e, +/-2e, +/-3e, etc.

The value of e is _______________

What is C? ______________________________________________

1.60x10-19 C

C is SI unit of electric charge called Coulomb

Insulator or Conductor?

Electrical Insulators? Electrical Conductors?

• Material in which charges can not move freely, hold charge in region of contact.• Examples:

• glass, rubber, silk, plastic, wood, paper

• Material in which charges can move freely, charge distributes itself over entire surface.• Examples:

• copper and aluminum

Semiconductors are materials that have electrical properties somewhere between conductors and insulators.

Silicon and germanium are examples

Methods of Charging by Contact

• Charged by Rubbing– Only the rubbed areas become charged– Works for insulators but not for conductors

• Charging by conduction– Charged object brought in contact with a neutral object – Neutral object becomes charged with same sign of charge as object doing the

charging.– Entire Region of object becomes charged.

Charging by Induction:• method used to charge an object without actually touching the object to any other charged object.• Neutral object becomes charged with opposite sign of charge as object doing the charging.• Only Conductors are charged by induction

Induction: the process of charging a conductor by brining it near another charged object and grounding the conductor.

Methods of Charging by Induction

Discharging by groundingNegative charge leaves (or enters) object through conducting path to Earth or other limitless reservoir of chargeThird opening of electrical outlets is the ground (connected to ground by wire and prevents static charge from building) When you ground something, you remove the excess electrons from the object. The charge is removed.

Methods of Discharging