2.1.1-electric fields-10/09/12

Static Electricity-stationary charges (normally electrons, sometimes protons) build up and Cause static electricity. The charge is normally built up by friction, like charges will repel one another unlike charges attract.

Vandergraph generator- these use a fan belt to transfer electrons on to a comb causing a build-up in charge. Air normally insulates this, however if moisture levels are high then it can conduct the electricity ionizing the air to pass on the charge this causes a spark and can be seen in lightning.

Electric fields- an electric field is the area on which the electrical/ charges force can act.

Common field interactions

1)

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This is a radial field showing protons (point charges) being attracted to a negative point of charge

2)

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Uniform or plate interaction- electric field near two parallel plates, one positive and the other negative and the uniform field between them (different at ends).

3)

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Null point- at a point the fields of two like charges cancel out at one point between them the location of which depends on the strength of fields at different distances

4) High density- one end has a higher build-up of charge so the field lines are denser (frequent). So more charge provides higher charges this has many applications

Electric field strength (E)

E= the force per unit charge at a point within an electric field

So E=F/Q the unit is newton per coulomb

E is a vector in the direction of F

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physics Apunte sobre Untitled_2, creado por jam123es el 10/04/2013.