ELECTRIC CHARGE

• property of matter that creates electric and magnetic forces and interactions.

• depends on the imbalance of its protons and electrons.

Electrons • negatively chargedprotons • positively chargedneutrons • are neutral (no charge).

ELECTRIC CHARGE

• Negatively charged objects have more electrons than protons.

• Positively charged objects have fewer electrons than protons.

SI unit:

• coulomb, C.

LAW OF CHARGES

• Like charges repel• opposite charges attract.

ELECTRIC CHARGE

ELECTRICAL CONDUCTOR:• material in which charges can move freely

and that can carry an electric current.

ELECTRICAL INSULATOR:• material that does not transfer current

easily.

CHARGING BY FRICTION

• When an object whose electrons are loosely held rubs against another object, electrons are transferred to the second object .

INDUCED CHARGES

• Electrons are moved to opposite ends (not by contact)

polarization• Alignment of charges at surface of an

object producing an electric charge• Positive & negative charges on opposite

sides

CHARGING BY CONTACT

When a negative rod touches a neutral doorknob, electrons move from the rod to the doorknob.

The transfer of electrons to the metal doorknob gives the doorknob a net negative charge.

•charge a neutral object by touching it with a charged object.

STATIC DISCHARGE• movement of

electrons to relieve a separation in charge

ELECTRIC FORCE

• force of attraction or repulsion between objects due to charge.

Electric force depends on charge and distance.

• proportional to product of charges on objects.

• inversely proportional to square of distance between two objects.

ELECTRIC FIELD LINES• point in direction of electric force on a positive

charge.• positive charge point outward.• negative charge point inward.• never cross one another.• show both direction of an electric field and relative

strength due to a given charge.• More lines are drawn for greater charges to indicate

greater force.

ELECTRIC FIELD LINES

ELECTRIC FIELD LINES