Saturday, 18 January 2014

PHYSICS 16/01/14


Electrical Insulators

- Hardly conduct electricity
- Electrons not free to move about/not mobile
- Easily gain or lose electrons, usually through rubbing (friction)
- Can be electrostatically charged by rubbing
- Cannot be charged using induction

Electrostatic charging by rubbing (friction)

- Rubbing (friction) causes electrons to be transferred.
- One material will be negatively charged as it gain electrons, the other material positively charged as it lose electrons.
- Electric charge can not be created or destroyed, only transferred from one material to another.
- Charges will stay on surfaces of material.


- Process that neutralize an electrically charged object by removing excess charge
- Heat: Ionizes surrounding air, neutralizing excess charges
- Humid Conditions: Water vapor in the air removes excess charges.

Electrical Conductors

- Conducts electricity
- Electrons are free to move about/mobile, not attached to any atoms
- Electrostatically charged by induction

Electrostatic charging by induction

- Charging without any contact with charging body.
- No charge is gained or loss by the charging body during the process.




- Earthing: provides a path for excess electrons to flow away or allow electrons to flow into the conductor.
- If conductor is positively charged, electrons flow from earth into conductor.
- If conductor is negatively charged, excess electrons flow out of the conductor to the earth
- 'Earth' refers to 'large' conductors that will not be noticeably charged when it lose or gain electrons.

1 comment:

  1. For charging by induction - "No charge is gained or loss by the charging body during the process." This statement is incorrect - if no charge is gained or lost, how can the body be charged in the end..??