Physics General Definitions - Electrostatics and Electromagnetism

The Law of Conservation of Electric Charge

The net charge of an isolated system remains constant during any physical process

What process can a charged object attract a neutral uncharged object?

Polarisation (electrostatic induction)

An object can only gain or lose whole number of electrons, so we say that electrc charge

is quantised

Difference between Q and q

-q experiances the force in an electric field

-Q creates this electric field

Right Hand Rule for Straight conductors

Hold the wire in your right hand so that your thumb points in the direction of the convectional current

Magnetic field around a solenoid is the same shape as..

The field around a bar magnet

Magnetic field INSIDE a solenoid

From South to North

Right Hand Rule for Solenoids:

If the solenoid is held in the right hand with your finger pointing in the diretion of the convectional current, your thumb points in the direction of the north pole of the solenoid

Danger of High voltage transmission lines with birds.

1. Electrocution

2.Collisions

Solution to Danger of high voltage tranmissions overhead.

Build the lines underground. Lines closer together, these fields interfere with eachothr and son net effect is less

The process where moving electric current induces a magnetic field

Electromagnetic induction

Farada'y Law of Electromagnetic Induction

The induced EMF in any closed system/circuit is equal to the rate of change of the magnetic flux through the circuit.

3 Factors which influence the magnitude of the induced emf or the induced current:

1) Stregth of the magnetic field

2) Number of turns of the coil

3) Speed of movement of the magnet

How do you know wheter an emf is induced?

galvanometer needle will be deflected.

Lenz's Law states:

The induced current flows to oppose the action producing it.

Magnetic Field

The space around a magnet in which other magnet materials will experiance a force

Magnetic Field Lines

The lines that show the magnetic field of a magnet.

Magnetic flux

The number of magnetic field lines passing through the surface area bounded by a closed solenoid loop. It is the "flow" of the magnet.

Magnetic flux density

The amount of magnetic flux through a unit area which is perpendicular to the direction of the flux.