202/1 – Know the principles of electricity

Outcome 1.1 – Reaction of electrons

Unit 202 Principles of electrical science

Unit 202 summative assessment

June 2015 (TBC)

Unit 202 Principles of electrical science

1.1 Describe the reaction of electrons when charged to form an electric current

This session

Electron flow

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CONVENTIONAL

ACTUAL

Molecules

Every known substance is made of molecules.

Every molecule is made of atoms.

Atom construction

Atoms consist of 3 different particles

Protons Electrons Neutrons

Atom construction

Each of these has a different electrical charge Protons ????????????? Electrons Neutrons

Atom construction

Each of these has a different electrical charge Protons positive (+ve) Electrons ??????????? Neutrons

Atom construction

Each of these has a different electrical charge Protonspositive (+ve) Electrons negative (-ve) Neutrons ???????

Atom construction

Each of these has a different electrical charge Protonspositive (+ve) Electrons negative (-ve) Neutrons neutral

Atom construction

As neutrons play no part in electricity at this level

of study, they can be ignored from now on

Atom constructionProtons are at the centre of an atom with the electrons orbiting around them.

Copper atom

Copper has 29 electrons orbiting 29 protons

Copper atom

But may look more like this:-

A conductor

A conductor has electrons far away from the protons in the

nucleus of an atom.

These electrons are easily moved from atom to atom and are called valence electrons.

A conductor

Copper (29)

A conductor

Aluminium (13)

A conductor

Silver (47)

Atom attraction

A positive magnet will attract a negative magnet,

The closer they are, the stronger the attraction

Atom attraction

This is the same within an atom, the electron is attracted towards the proton

The closer they are, the stronger the attraction

Atom attraction

In a copper atom, the single electron furthest from protons has the least attraction

Atom attraction

This electron is easily moved from atom to

atom and is the flow of electricity.

Electron flow between atoms

https://www.youtube.com/watch?v=KprFTxjQAoE

Video

IF…….

6,241,509,629,152,650,000

electrons flow

This equals one coulomb

If 1 coulomb flows in 1 second this equals 1 amp

Measurement of electrical current flow

six quintillion, two hundred forty-one quadrillion, five hundred nine trillion, six

hundred twenty-nine billion, one hundred fifty-two million, six hundred

fifty thousand

In words

1.1 Describe the reaction of electrons when charged to form an electric current ?

A current will flow when an electro motive force is connected to a complete circuit.

Consolidation

1.2 Identify sources of an electromotive force

1.3 Describe the effects of an electric current

Chemical, magnetic, thermal.

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