Principles of electricity

• newEditor
• Electrical Principles
• Higher Education (non-degree)

Principles of electricity

1. Understand standard units of measurement used in electrical installation, maintenance and design work

2. Understand the relationship between resistance, resistivity, voltage, current and power.

Assessment criteria

The learner can:

1. Identify and use internationally recognised base and derived (SI) units of measurement

2. Identify and determine values of base and derived SI units which apply specifically to electrical quantities

3. Describe the basic principles of electron theory

4. Identify and distinguish between materials which are good conductors and insulators

5. Describe the chemical and thermal effects of electric currents

Range

(SI) units of measurement: length, area, volume, mass, density, time, temperature, velocity

Electrical quantities (SI units): resistance, resistivity, power, frequency, current, voltage, energy, impedance, inductance and inductive reactance, capacitance and capacitive reactance, power factor

Electron theory – structure of matter

The smallest part of any material is called a molecule, yet the latter is made up of one or more atoms. For example, water is made up of H₂O (two atoms of hydrogen and one atom of oxygen).

Basically, the atom is constructed of a central core containing protons surrounded by orbiting electrons.

Protons are positively charged.

Electrons are negatively charged.

Principles of electricity

In an electrically neutral atom,

The number of protons is equal to the number of electrons.

The simplest atom is hydrogen (1 proton and 1 electron) – see right.

The heaviest atom is uranium (92 protons balanced by 92 electrons).

Helium atom (two protons and two electrons).

   Name the two main parts of the atom.

Electron

Photon

Neutron

Nucleus

What Element of the Atom is negativily charge

A

Photon

B

Neutron

C

Electron

D

Nucleus