08/2 – Understand standard units of measurement used in electrical installation, maintenance and

design work.

Outcome 2.1/2.2 – Standard form (SI) and formula transposition

Unit 08 Principles of electrical science

1.1 Understand mathematical principles which are appropriate to electrical installation, maintenance and design work.

Last session

2.1 - Identify and use internationally recognised (SI) units of measurement for general variables.

2.2 - Identify and determine values of basic SI units which apply specifically to electrical variables.

Current, potential, resistance, resistivity, temperature, force, magnetic flux, magnetic flux density, period, frequency, power, energy, time, length, area, mass, weight.

1.1 - Transpose basic formulae. (reminder)

This session

Current

Potential

Resistance

Current, potential, resistance

Formula (triangle)

Current, potential, resistance

Current

Potential

power

Current, potential, power

Formula (triangle)

Current, potential, power

Resistivity

Area

Length

Resistivity, length and area

Formula

Resistivity, length and area

Resistivity of common materials

period, frequency and time

Periodic time

Frequency

period, frequency and time

period, frequency and time

Formulas?

magnetic flux, magnetic flux density and area

magnetic flux, magnetic flux density and area

Magnetic flux is how strong a magnet is.

Magnetic flux is given the symbol Φ and is measured in units called Webers (Wb).

magnetic flux, magnetic flux density and area

Magnetic flux density is how much magnetism there is in an area

Magnetic flux density is given the symbol B and is measured in units called Telsas (T).

magnetic flux, magnetic flux density and area

FormulaFlux (Φ) = Flux density (B) x area (A)

Φ = BA

Transpose

Mass and weight

What is the difference between mass and weight?

Mass = 80 kg Mass = 80 kg

Weight = 0 Weight = 80 × gravity

Mass and weight

Gravity on earth = 9.81m/s²

Gravity on moon = 1.62m/s²

Mass and weight

Formula

Weight (N) = mass (kg) x gravity (9.81)

Transpose

Mass and weight

Earth Moon Mercury Venus Mars Pluto

Surface Gravity(compared to

Earth)1 0.17 0.38 0.90 0.38 0.06

How muchyou can lift

10 kg

60 kg 30 kg 10 kg 30 kg 170 kg

How highyou can jump

20 cm

120 cm

53 cm 22 cm 53 cm 340 cm

How long it takes to fall back to the

ground0.4 s 2.4 s 1.1 s 0.4 s 1.1 s 6.8 s

How far youcan kick a ball

20 m 120 m 53 m 22m 53 m 340 m

ForceMeasured in Newtons (N)

Distance Measured in metres (M)

EnergySame as work done measured in Joules(J) symbol W

Force, distance and energy

FormulaWork done/energy(Joules) = Force(N) x Distance(m)

transpose

Force, distance and energy

2.1 - Identify and use internationally recognised (SI) units of measurement for general variables.

2.2 - Identify and determine values of basic SI units which apply specifically to electrical variables.

Current, potential, resistance, resistivity, temperature, force, magnetic flux, magnetic flux density, period, frequency, power, energy, time, length, area, mass, weight.

1.1 - Transpose basic formulae. (reminder)

Consolidation

Outcome 1 formative assessment

Next session