static and charge

• when two objects are rubbed together, friction causes electrons to move from one object to another, this can lead to a build up of charge.

  however, this doesn't work for friction between two conducting materials because the electrons would just flow straight out.
• when two materials are rubbed together, electrons are transferred
• a large build up of charge can cause a large potential difference between the object and the earth.

  the large potential difference could allow electrons to jump through the air, causing a spark.
• all charged objects have an electric field
• field lines always point from positive to negative charge.
•  Electric fields are strongest when close to the charged particle, and get weaker further away from the charged particle.
• current: measure of flow of electrons [around the circuit]
• potential difference: force driving the flow of electrons around the circuit