A summary of electrical technology including the differences between an electrical and electronic system, atomic theory, conductors/insulators/semi-conductors, and revision of basic electrical terms and circuits. You won't regret buying these notes!
Electrical Technology
Application based, don’t learn word for word
Impact of electricity (flow of energy) – we can’t live without it!
Comes from natural resources: Coal, hydropower, sun
Power station (starting place)- where electricity comes from
The Differences between an Electrical and
Electronic System
Electrical Systems
Often supply electricity to a machine
Have no level of intelligence
Usually work on higher voltage levels
Have one input and one output
An electrical drill is an example of an Electrical System
Electronic Systems
Have a level of intelligence e.g. switching on a device etc.
Work on smaller voltage levels
Have multiple inputs and outputs
A cell phone is an example of an Electronic System
ELECTRONIC – Multiple inputs and outputs (Many uses & purposes)
POWER ELECTRONIC – e.g. microwave (can do a purpose along with other things)
ELECTRICAL- 1 Input, 1 Output
Alternating Current – the type of electricity that comes from a plug
(AC) Changes polarity
Direct Current – comes from a battery (Portable)
(DC) Does not change polarity
Oscilloscope – An instrument to measure the current
Atomic Theory
Electricity – the movement of a valence electron from one atom to another
Protons (+) positively charged
Neutrons are uncharged
Electrons are -ive (negatively) charged
Building blocks of Matter – occupies space & has mass
Atomic theory is the scientific theory of the nature of matter.
Matter is made up of small particles called atoms.
Atoms consist of even smaller particles called electrons, protons and neutrons.
, Nucleus - protons and neutrons form the central part of this.
When two, three or more atoms form chemical bonds with each other, they form
molecules.
Atoms can be the same or different from each other in one molecule
Like (the same ) charges repel each other and unlike (different) charges attract each
other.
In an electric circuit the electrons (negative charges) will flow away from the negative
terminal of the battery or other power supply and they move towards the positive
terminal.
Called the Electron flow direction
Any free positive charge (e.g. positive ions, cat-ions, holes and protons) were to move
in a circuit - they would move away from the positive terminal of the battery towards the
negative terminal of the battery.
Called conventional flow direction of current.
Current flow (l) is the rate of flow of charge (Q).
Charge is measured in units called Coulombs and current is measured in Amperes
(Amps)
l= Q
t Q=l x t
Nucleus
Consists of positively charged protons and uncharged neutrons.
More or less the same size and weight.
Nuclear glue” that holds the nucleus together and is called nuclear forces
There may also be a sub-nuclear particle called a gluon that holds the nuclear together.
Electrons
To keep an atom electrically stable, it must have an equal number of electrons
(negative) in orbit around the nucleus of protons (positive) in the nucleus.
Atom called an ion - when there are either more or less electrons in orbit compared to
protons in the nucleus.
Happens in static electricity and in some chemical solutions.
Electron Shells
When electrons are arranged in shells or orbits around the nucleus.
Electrons have different amounts of energy.
Valence shell
The outer most shell of any atom
Valence electrons
These are the electrons in the outer most shell or energy level of an atom.
These are the electrons that take part in forming chemical bonds.
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