Electric Charge MATTER AMBER a hard translucent fossil

Electric Charge

MATTER

AMBER a hard translucent fossil resin varying in color from yellow to light http: //witchcraftsupplies. com/Prod 4/amber_insect 1. j pg http: //commons. wikimedia. org/wiki/ File: Amber. pendants. 800 pix. 05020 3. jpg

BENJAMIN FRANKLIN INTRODUCED THE IDEA THAT ALL SUBSTANCES ARE PENETRATED BY AN ELECTRIC FIRE TOO MUCH ELECTRIC FIRE= POSITIVE CHARGE LACK OF ELECTRIC FIRE= NEGATIVE CHARGE

Electrostatics The study of the interactions between electric charges that are at rest (or nearly so).

ELECTRIC CHARGE �Fundamental quantity in electrostatics �Two kinds of charge: positive and negative

Elementary Charge

Electric Attraction and Repulsion LIKE CHARGES REPEL: Two positive charges repel each other Two negative charges repel each other UNLIKE CHARGES ATTRACT: Negative charge attracts positive charge.

Law of Conservation of Charge • THE NET AMOUNT OF CHARGE PRODUCED IN ANY PROCESS IS ZERO; • NO NET ELECTRIC CHARGE CAN BE CREATED OR DESTROYED

Conductors, Insulators, and Ground �Conductor- material that permit the flow of electric charge �Insulator- material that do not allow the flow of electric charge readily �Ground- a neutral material that can accept or supply an essentially unlimited number of

PLEASE SEE VIDEO DEMONSTRATION

CHARGING PROCESS �CONDUCTION- charging neutral object by placing charge object in contact with the neutral object �INDUCTION- charging neutral object by placing charge object near the neutral object without physical contact

INDUCTION PROCESS

INDUCTION PROCESS

ELECTROSCOPE • A device that can be used for detecting charge a, ab c d - thin leaves of metal foil - metal support - glass container - metal knob

COULOMB’S LAW Ø Applicable to point charges (objects whose size is much smaller than the distance between them) Ø Describes the interaction of electric charges

EX 1. ELECTRIC FORCE ON ELECTRON BY PROTON Determine the magnitude and direction of the electric force on the electron of a hydrogen atom exerted by the single proton that is the atom’s nucleus. Assume the average distance between the revolving electron and the proton is r= 0. 53 x 10 -10 m.

EX 2. WHO IS STRONGER? � Two point charges, q 1= +25 n. C and q 2= 75 n. C, are separated by a distance of 3. 0 cm. Find the magnitude and direction of a) The electric force that q 1 exerts on q 2; and b) The electric force that q 2 exerts on q 1.

PRINCIPLE OF SUPERPOSITION OF FORCES States that when two or more forces exerted by two or more charges on a charge, the total force on that charge is the vector sum of the forces exerted by the individual charges.

VECTOR ADDITION OF ELECTRIC FORCES ON A LINE Two point charges are located on the positive x axis of a coordinate system. Charge q 1 = 1. 0 n. C is 2. 0 cm from the origin, and charge q 2 = - 3. 0 n. C is 4. 0 cm from the origin. What is the total force exerted by these two charges on a charge q 3 = 5. 0 n. C located at the origin? Gravitational forces are