NZQA registered unit standard
25072 version 3
Page 1 of 4
Title
Demonstrate knowledge of electromagnetism theory
Level
2
Purpose
Credits
5
This unit standard covers knowledge of electromagnetism
theory which underpins all technical careers in the electrical
and electronic industries.
People credited with this unit standard are able to demonstrate
knowledge of:
–
magnets and magnetism;
–
a.c. generation;
–
d.c. generation; and
–
the simple d.c. motor.
Classification
Electrical Engineering > Core Electrical
Available grade
Achieved
Entry information
Recommended skills
and knowledge
Unit 25070, Explain the properties of conductors, insulators,
and semiconductors and their effect on electrical circuits, and
Unit 25071, Demonstrate knowledge of electromotive force
(e.m.f.) production; or demonstrate equivalent knowledge and
skills.
Explanatory notes
1
This unit standard has been developed for learning and assessment off-job.
2
This unit standard is one of three designed to cover knowledge of magnetism and
electricity, the others being Unit 25070, Explain the properties of conductors,
insulators, and semiconductors and their effect on electrical circuits, and Unit 25071,
Demonstrate knowledge of electromotive force (e.m.f.) production.
3
Definitions
a.c. – alternating current.
d.c. – direct current.
e.m.f. – electromotive force.
r.m.s. – root-mean-square.
4
For assessment purposes:
a Candidates shall be supplied with formulae involving more than three quantities.
b Use of a calculator during assessment is permitted.
The Skills Organisation
SSB Code 100401
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
25072 version 3
Page 2 of 4
c Candidates are expected to express calculated values in the relevant Système
International (SI) units, including multiples and sub-multiples (pico (p) 10-12 ; nano
(n) 10-9; micro (μ) 10-6; milli (m) 10-3; kilo(k) 103; mega (M) 106; etc) and to be
able to convert between them.
5
Formulae quoted in this unit standard use internationally recognised symbols and
units.
6
Conventional current flow direction (positive to negative) is implied. Trainees should
be aware of the opposite direction of electron flow.
Outcomes and evidence requirements
Outcome 1
Demonstrate knowledge of magnets and magnetism.
Evidence requirements
1.1
Magnetic terms are explained in relation to permanent magnets, in accordance
with industry practice.
Range
1.2
permanent magnet, magnetic field strength, lines of force,
magnetic poles, magnetic flux, flux density.
The direction of the magnetic field surrounding a current carrying wire is
determined using any popular rule.
Range
any popular rule may include but is not limited to – the right-hand
screw rule.
1.3
The construction of an electromagnet is described with the aid of a sketch
indicating current direction and magnet polarity.
1.4
The transformer principle is explained in terms of induced e.m.f. resulting from
changing flux linkages.
1.5
Devices using electromagnetic and magnetic properties are described in simple
terms.
Range
1.6
any two of – loudspeaker, relay, electric bell, moving coil
instrument, lifting magnet, electric door lock.
The purpose and application of magnetic screening is stated in terms of
protection of sensitive meters and circuitry from magnetic interference.
The Skills Organisation
SSB Code 100401
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
25072 version 3
Page 3 of 4
Outcome 2
Demonstrate knowledge of a.c. generation.
Evidence requirements
2.1
The operation of a simple single-loop, two-pole alternator with slip-rings and
brushes is described with the aid of a sketch.
2.2
Alternator output for each quarter-cycle through one revolution is described with
the aid of a sketch, and shows a completed resultant waveform.
2.3
A.c. terms are defined in accordance with industry practice.
Range
cycle, period, frequency, peak, average, instantaneous, r.m.s.
2.4
The reason for using the r.m.s. value of an a.c. wave form is stated in terms of
the equivalence of r.m.s. and steady d.c. values for resistive heating effect.
2.5
Values are calculated from a.c. voltage and current wave form data.
Range
peak, average, r.m.s., frequency, period.
Outcome 3
Demonstrate knowledge of d.c. generation.
Evidence requirements
3.1
The induction of an e.m.f. in a conductor being moved in a magnetic field is
demonstrated using Fleming's right-hand rule.
3.2
The operation of a simple direct current generator is explained with the aid of a
sketch.
Range
3.3
simple generator – permanent magnet, single loop of wire, twosegment commutator, carbon brush.
Generator output for each quarter-cycle through one revolution is described and
shows a completed resultant waveform.
Outcome 4
Demonstrate knowledge of the simple d.c. motor.
Evidence requirements
4.1
The direction of the force exerted on a current carrying conductor in a magnetic
field is determined using any popular rule.
Range
The Skills Organisation
SSB Code 100401
any popular rule may include but is not limited to – Fleming's lefthand rule.
 New Zealand Qualifications Authority 2016
NZQA registered unit standard
4.2
25072 version 3
Page 4 of 4
The operation of a simple motor is explained with the aid of a sketch showing
direction of current and polarity of the magnet.
simple motor – permanent magnet, single loop of wire, twosegment commutator, carbon brush.
Range
Replacement information
This unit standard, unit standard 25070, and unit standard
25071 replaced unit standard 15843.
Planned review date
31 December 2014
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
22 August 2008
N/A
Rollover and
Revision
2
15 March 2012
N/A
Revision
3
15 January 2014
N/A
Consent and Moderation Requirements (CMR) reference
0003
This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA,
before they can report credits from assessment against unit standards or deliver courses
of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and
which are assessing against unit standards must engage with the moderation system that
applies to those standards.
Requirements for consent to assess and an outline of the moderation system that applies
to this standard are outlined in the Consent and Moderation Requirements (CMR). The
CMR also includes useful information about special requirements for organisations wishing
to develop education and training programmes, such as minimum qualifications for tutors
and assessors, and special resource requirements.
Comments on this unit standard
Please contact The Skills Organisation reviewcomments@skills.org.nz if you wish to
suggest changes to the content of this unit standard.
The Skills Organisation
SSB Code 100401
 New Zealand Qualifications Authority 2016