Static electricity, Coulombs Law

• Coulomb's law states that the magnitude of the electrostatic force between two point charges is equal to kq1q2/r^2, where q1 and q2 are the magnitudes of the charges, r is the distance between them, and k is a constant called the Coulomb constant (k = 8.9875 x 10^9 Nm^2/C^2).
• The force between two charges is inversely proportional to the square of the distance between them.
• The force between two charges is directly proportional to the product of their magnitudes.
• If both charges have like signs (+ or -), then they repel one another.
• If both charges have unlike signs (- and +), then they attract one another.
• The direction of the force is along the line joining the centers of the two charged objects.
• Electrostatics refers to the branch of physics dealing with electric charge at rest or in slow motion.
• Charges can be transferred from one object to another through contact, induction, or conduction.
• Coulomb's law states that the magnitude of the electrostatic force between two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance separating them.
• A conductor allows electrons to move freely throughout its structure.
• When objects rub against each other, electrons can be transferred from one object to another, resulting in static electricity.
• Conductors are materials that allow electrons to move freely within them.
• The unit of electrical charge is coulomb (C).
• Insulators do not conduct electricity because there are no free electrons available to carry an electrical current.
• The formula for calculating the force between two point charges is F = kq1q2/r^2
• Static electricity is the accumulation of electric charge on the surface of, or within, a material.
• The shock happens when the extra electrons move and are released or discharged from an object, such as your finger to the light switch.
• Charge doesn't have to be moving, it's still there even when it's resting on an object.
• One example of electrostatic force is car painting, where robots use an electrostatic sprayer to paint cars, charging the paint particles with extra electrons, giving them a negative charge.
• The surface of the car is positively charged, so when the negatively charged paint droplets are pushed through the sprayer, they are attracted to the car's positively charged surface.
• For electrostatic painting to work well, workers wear lint-free clothing so they don't attract the paint instead of the car.
• Charge is a basic property of matter, like mass, and all matter has a charge, which can be positive, negative, or neutral.
• At the atomic level, protons have a positive charge, and electrons have a negative one, with charges on a proton and electron being equal in magnitude and opposite in sign.
• When an object's charge is all balanced out, it is said to be neutral.
• Every charge creates a field around it, which we call an electric field, and other charges in the field will feel a pull if the charges are opposite, and a push if the charges are the same.
• Metal, like in cars, is one of the better conductors of electricity, and an insulator, like a car's tires, is a material that resists the movement of charge.
• Even if objects start out neutral, there are several ways we can give them a negative or positive charge.
• To charge by friction, an uncharged balloon is hung by an insulating thread, a glass rod, and some fur, and when the fur is rubbed on the glass rod, the glass becomes positively charged, and the fur gains a net negative charge.
• The Triboelectric Series is a list of materials that ranks materials on how easily they give up or receive electrons, with fur being higher up on the list, meaning when fur and glass are rubbed together, the glass becomes positively charged, and the fur gains a net negative charge.
• Conduction is a way to accumulate charge by transferring charge by direct contact.
• When the glass rod makes contact with the sphere, the sphere gains positive charge.
• Precipitators are electrostatic machines used in industrial plants to capture up to a large percentage of the particles from the burning material, though some pollution does escape.
• The law of conservation of charge states that electric charge cannot be created or destroyed, but can be transferred from one object to another.
• The electroscope now has a positive charge.
• When a charged glass rod is touched to the top of an electroscope, electrons move from the electroscope to the rod, making the foil leaves at the bottom both positively charged, and they repel each other.
• A piece of paper, which has been given a charge, rolls over this area.
• The leaves are straight down, not attracting or repelling each other.
• The electrostatic force, like other forces, is conservative, meaning it cannot be created or destroyed.
• Induction is when a neutral object is charged by bringing a charged object close to but not touching the object.
• When a charged glass rod is brought close to an electroscope, it causes the positive charges in the electroscope to be repelled and to accumulate in the foil leaves.