ELECTRICITY
charging and discharging
electrostatic phenomena
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triboelectric effect: caused by fiction. when you rub one object against another, the one higher on the tb scale will loose electrons and the one lower will gain those electrons.
induction: charge without contact.
when you bring an object that is charged close to another object that is neutral it gets induced with the opposite charge.
conduction: charge by contact. when an already charged object comes in contact with another object therefore the second object gains the similar charge.
types of materials
conductors: allow electricity to pass
insulators: dont allow electricity to pass.
example: wood, glass
dangers of electricity
sparks and current: if enough charge builds up due to friction, then a spark will form. air does not usually a current to flow through. it takes a lot of charge to build up. negative charges formed due to the movement of air at the bottom of the thunder cloud make huge sparks as they travel to earth. we see that lightning. if this happens within the cloud it can light up the cloud.
if this strikes person, the charges can travel through them and intefere with their heart, killing them
electrostatic wristbands: engineers making delicate circuits wear these bands connected to a metal wire that goes to the ground. any build up of the charge flows down the wire instead of through components
reducing this risk: lightning conductors: thick strip of metal like copper running down the wall attached to a copper plate buried underground. this metal conducts electricity better than the building.
fuel pipes are earthed by attaching a metal wire to the pipe. build of charge when the fuel travels down the pipe (due to friction) will travel to earth and reduce risk of spark.
electric circuits
parallel circuits and series circuit: 
components
volatge: current multipled by resistence
resistence: voltage upon current
current: voltage upon resistence
units:
WD= jules (J)
I=current (A)
V= volatge (v)
Q=charge (C)
P=power (watts)
R= resistence (ohms)
T=time (s)