Presentation on theme: "Electrostatics Electrostatics – electricity that does not move or is static All electricity comes from electrical forces from atoms -Atoms contain protons."— Presentation transcript:
Electrostatics Electrostatics – electricity that does not move or is static All electricity comes from electrical forces from atoms -Atoms contain protons that are positive and electrons that have a negative charge -The accumulation of electrons is were electricity comes from
Making an Object Gain a Charge Because all objects are made of atoms, all objects have protons and electrons -If an object gains extra electrons from an outside source that object becomes negative -If an object loses electrons it will have more protons than electrons so it will have a positive charge -An object with an unequal number of protons and electrons will have a charge!
How Charges Interact Two objects with the same charge will repel - two positively charged objects will push each other away or repel - two negatively charged objects will push each other away or repel - two objects that have opposite charges (one positive and one negative) will attract or be drawn together.
Where do the electrons end up on a new object? Can you set in a car that is being struck by lightning and still be safe? Why or Why not? The electrons are on the outer edge of the car because they are all negative and push each other away. The inside of the car has no charge so you will be OK. N7s
Conservation of Charge Conservation of Charge – electrons are neither created or destroyed but as simply passes from one material to another
Coulomb’s Law Coulomb’s Law – the relationship between electrical force, charges, and distance -For charged particles or objects that are small compared with the distance between them, the force between the charges varies directly as the product of the charges and inversely as the square of the distance between them -The particles will get pushed apart or pulled together more if they have a greater charge -The particles will get pushed apart or pulled together less if they are farther apart
Coulomb’s Law F = k q 1 q 2 / d 2 Where; -F means force of force of attraction or repulsion -k is the proportionality constant (9.0 x 10 9 Nm 2 /C 2 ) -q is the charge on a particle ( 1 means the first particle 2 means the second particle -d is the distance between the particles in meters
Coulomb Coulomb (C)– the unit or measurement of charge Two pellets, each with a charge of 1µC, are separated by a distance of 0.30m. What is the electric force between them? 1µC = 1x10 -6 C F = k q1 q2 / d 2 F = (9x10 9 ) x (1x10 -6 ) x (1x10 -6 )/(0.30)x(0.30) F = 0.1N
Ways to charge a particle 1.By friction and contact 2.By induction
Charging by Friction and Contact As you rub one object on another electrons leave one object and go to the other. The object that the electrons go to get a negative charge. You can discharge the negative object by touching it to a neutral object.
Charging by Induction If a charged object is brought near a conducting surface, even without physically touching, electrons will move in the conducting surface. Induced – an object that redistributes its charges because of the presence of a charged object nearby Induction – the charging of an object without direct contact
Grounding Grounding – when charges are allowed to move off (or onto) a conductor by touching it - When we see lightning we are seeing grounding happen. The clouds have built up a negative charge. To get rid of the negative charge lightning (electrons) come from the cloud and touch the Earth grounding the cloud
Electrical Polarization Electrical Polarization – when one side of an atom or molecules is induced to be slightly more positive (or negative) than the opposite side -Charge polarization can occur in insulators that are near a charged object. -This is why a charged balloon (which was charged by rubbing on your hair) can stick to a wall. The negatively charged balloon polarizes the wall