UNIT REVISION

City & Guilds 2365-02 Unit 202: Principles of Electrical Science — Complete Revision Guide

A structured revision walkthrough of every topic in City & Guilds 2365-02 Unit 202 (Principles of Electrical Science). Use it as a personal study checklist — work through each topic, tick off the points you can confidently explain or calculate, and use the linked Elec-Mate tools to practice the calculation-led parts. Designed for 1st-year apprentices.

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9 min readUpdated 2026-05-18Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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Key Takeaways

  • 1City & Guilds 2365-02 Unit 202 — Principles of Electrical Science — is a core component of the Level 2 Diploma in Electrical Installations.
  • 2This unit is typically delivered to 1st-year apprentices and covers 6 main topic areas.
  • 3Across the 6 topics there are 23 specific points you should be able to explain, demonstrate or calculate before the end-of-unit assessment.
  • 4Common assessment formats include online multiple-choice exams, written short-answer papers, and practical workshop tasks observed by your tutor.
  • 5Use the structured topic list below as a personal checklist — work through each point and confirm you can explain it without referring to your notes.
  • 6The Elec-Mate apprentice tier includes mock exams, flashcards, and revision notes mapped to this unit. Use the tools to test yourself between college blocks and on-site days.
01 · Unit Revision

Topic 1: Mathematical principles which are appropriate to electrical installation, maintenance and design work

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Identify and apply appropriate mathematical principles which are relevant to electrical work tasks.
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02 · Unit Revision

Topic 2: Standard units of measurement used in electrical installation, maintenance and design work

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Identify and use internationally recognised base and derived SI units of measurement.
  • Identify and determine values of base and derived SI units which apply specifically to electrical quantities.
  • Identify appropriate electrical instruments for the measurement of different electrical quantities.
03 · Unit Revision

Topic 3: Basic mechanics and the relationship between force, work, energy and power

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Specify what is meant by mass and weight.
  • Explain the principles of basic mechanics as they apply to levers, gears and pulleys.
  • Describe the main principles of force, work, energy (kinetic and potential), power, and efficiency and their inter-relationships.
  • Calculate values of mechanical energy, power and efficiency.
04 · Unit Revision

Topic 4: The relationship between resistance, resistivity, voltage, current and power

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Describe the basic principles of electron theory.
  • Identify and distinguish between materials which are good conductors and insulators.
  • Describe what is meant by resistance and resistivity in relation to electrical circuits.
  • Explain the relationship between current, voltage and resistance in parallel and series DC circuits.
  • Calculate the values of current, voltage and resistance in parallel and series DC circuits.
  • Calculate values of power in parallel and series DC circuits.
  • State what is meant by the term voltage drop in relation to electrical circuits.
  • Describe the chemical and thermal effects of electric currents.

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05 · Unit Revision

Topic 5: The fundamental principles which underpin the relationship between magnetism and electricity

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Describe the effects of magnetism in terms of attraction and repulsion.
  • State the difference between magnetic flux and flux density.
  • Describe the magnetic effects of electrical currents in terms of production of a magnetic field, force on a current-carrying conductor, electromagnetism, and electromotive force.
  • Describe the basic principles of generating an AC supply in terms of a single-loop generator, sine-wave, frequency, EMF, and magnetic flux.
  • Identify the characteristics of sine-waves.
06 · Unit Revision

Topic 6: The types, applications and limitations of electronic components in electrical systems and equipment

In this section you should be confident with the following points. Each one is a specific topic you should be able to explain, demonstrate, or calculate.

  • Describe the function and application of electronic components that are used in electrical systems.
  • State the basic operating principles of electronic components and devices.
07 · Unit Revision

Study This Unit with Elec-Mate

Elec-Mate’s apprentice tier turns this unit checklist into an active study plan. You get mock exam questions, flashcards, and revision notes mapped to this unit, plus working calculators for every calculation-led topic. Most apprentices use the app between college blocks and on the train to site — short bursts of revision compound across the year.

For apprentices

The Elec-Mate apprentice tier includes mock exams, flashcards, and revision notes for City & Guilds 2365-02 Unit 202 plus every other unit in your qualification. 7-day free trial — see your progress on the tutor dashboard.

A Five-Step Revision Plan for This Unit

A repeatable approach that works for City & Guilds 2365-02 Unit 202 and every other unit in your qualification.

1

Read through every topic point once

Start at Topic 1 and read every bullet point. Don’t try to memorise — just get familiar with the scope. Note any topic that feels unfamiliar so you can come back to it.

2

Map each topic to its calculator or guide

For calculation-led topics, open the relevant Elec-Mate calculator and try one worked example. For theory-led topics, find the matching section in BS 7671 or the IET On-Site Guide.

3

Work through Elec-Mate mock exam questions

The Elec-Mate apprentice tier includes mock questions mapped to this unit. Aim for 80%+ on a clean run before the real exam.

4

Get hands-on time on the bench

For practical units (inspection and testing, installation), ask your tutor for additional workshop access. The bench is where the points click.

5

Self-explain each topic to a peer

If you can explain a topic in your own words to another apprentice and they understand it, you know it. This is the single highest-leverage revision tactic.

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