P3.1 - Static and Charge

• When two insulators are rubbed against each other, electrons are transferred from one to the other. On object ends up with an excess of electrons and becomes negative, and the other has lost electrons and becomes positive.
• In polythene rods, electrons are gained. In acetate rods, electrons are lost.

  
• To discharge an object (remove its charge) it needs to be connected to something that allows the charges to flow.
• Sparks discharge objects, such as a Van der Graaf generator or clouds. A spark is a flow of charge (current) through air.
• If you add a charged object to a field, the field lines will stretch. The force on the object is in the direction that causes the field lines the shorten.
• The direction of the field lines is the direction of the force on a positive charge.
• Current is the flow of charged particles (charge).
• For a current to flow, it needs a power supply and a circuit.
• Current is the same at any point of a singe closed loop.
• Conventional current is the flow of charge from the positive terminal to the negative terminal of a battery. It is in opposition to electron flow.
• Charge flow (Coulombs) = current (A) * time (s)
• 1 mA = 1*10^-3 A