When protons and electrons
do not balance in an object, the objects becomes electronically charged.
Static electricity occurs when a charge is isolated on an object by insulating material.
MORE electrons in an object= NEGATIVELY charged object
LESS electrons in an object= POSITIVELY charged object
When an object is rubbed by another electrons are transferred.
If one or both are insulaters, then static electricity occurs.
LAW OF CONSERVATION OF CHARGE
Charge cannot be created nor destroyed. Charge is transferred from one object to another.
What is an ELECTRIC FIELD?
The region in space where a charged object will experience an electrostatic force.
Forces between objects...
Opposite charges attract, and like charges repel.
The size of the electrostatic force depends on...
The amount of charge
Distance between the objects
Charge of 1 electron...
1 electron has a charge of -1,6*10 to the -19 C (coulomb)
Insulators and conductors...
Conductors are materials that allow electrons to pass through them. This could occur because electrons are free to move and carry charge ( delocalised).
An insulator does not allow charge to move through it since electrons are in fixed positions. eg. wood.
You also get semiconductors, which are in-between materials. They are poor conductors when hot, but better conductors when cold.
Conduction of Charge...
When a charged object is brought into contact with an uncharged object, part of its charges flow into the uncharged object and makes it partially charged.
The transfer proportion depends on the shapes of the two objects.
Therefore if two identical metal spheres, they would share the charge equally.
If a positively charged rod is close to an insulator, not toughing, it attracts the electrons within the individual atoms (or molecules) of the insulator. It's a very small effect, but there are many atoms and if the polarised object is light, there can be sufficient force to attract it to the rod. The insulator would not be charged, but just polarised.
When a charged object is brought near to the pan, some of the charge gets transferred to the foils via the metal rod. The foils become charged up with like charged that repel each other causing the foils to separate and and open up.
Detection of charge...
Electrostatic charge can be detected by using a gold leaf electroscope.
A Gold Leaf Electroscope has a glass compartment with a metal rod inserted into it. The end of the rod that is inside the compartment has two small metal (aluminium or gold) leaves hinged onto it. The outer end is connected to a metal pan.
A region in which an electric charge experiences a force.
1. They start on positive charges and end on negative charges.
2. They never cross
3. The are 3- dimensional
4. The denser the field lines the stronger the field
5. They enter and leave charged objects at right angles.
6. They are contiuous