Electrostatics Electric charges the forces between them and

Electrostatics Electric charges, the forces between them and their behavior in materials.

Electrical Forces ü Come from charges in atoms. ü All electrons are identical. ü Protons charge is equal and opposite of electrons in an atom. ü Atoms are usually neutral.

Fundamental Rule Of Electrostatics Opposite charges attract. Like charges repel.

Conservation of Charges can be transferred but never destroyed! Equal numbers of charged particles result in a neutral object. Cl All charges are whole number multiples of the charge of a single electron! Unequal numbers of charged particles result in a charged object. Cl-

What causes an object to have an electrical charge? 1. An object that has unequal numbers of electrons and protons is electrically charged. 2. Friction between two objects can build an electrical charge. 3. An uneven distribution of protons and electrons in an object can cause it to have oppositely charged sides.

Electricity Touching a charged object to another object “discharges” the extra electrons. Conductors Insulators Allow electrons to move Do not allow electrons easily. to move easily.

Electric charge can be transferred. Friction Sliding on the car seat to get out. Walking on new carpet. Drying clothes in the dryer. Contact Ø Touching the car door after you are out of the car. Ø Touching someone after you walk on the carpet. Ø Folding the clothes. Induction q Bringing a charged object near a neutral object causing the electrons to move to one side of the object

Stick a balloon on the wall. Friction creates a negative charge on one side of an insulator. Polar induction occurs when you bring it near the wall surface.

Charging By Induction

Induction Bringing a charged object near another object without touching it. Try bending water with a charged comb.

Lightning Strikes Cloud to cloud lightening is most common. Clouds have negatively charged bottoms that induce a positive charge on the earth. The original lightening rods increased the number of fires in the buildings they were attached to. The lightening rod has to be grounded. Giving electricity a path directly to the ground prevents sudden charge between buildings and clouds.

Ben Franklin’s Success Was Failure! Failure to be struck by lightning. Ben’s kite string was able to pick up and demonstrate a charge without being struck by lightning. The next two scientists that tried to duplicate his experiment did die from lightning strikes.

Coulomb’s Law The force between two electrically charged objects depends on the magnitude and the distance between the charges. F = k Q 1 Q 2 r 2

What are three ways to transfer charge?

1. Friction, 2. Contact, 3. Induction

Electrical Force • The electrical constant, k is 9 000 000 N. m 2/C 2 • 200 billion times stronger than gravity of the earth. • Distances between charged particles are small compared the charges between them.