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RAF Airman/Airwoman Selection Test (AST) Electrical Comprehension Flashcards
50 question-and-answer cards covering Electrical Comprehension as it is examined in RAF Airman/Airwoman Selection Test (AST). 24 of them are printed below, taken from across the deck — no signup, no paywall on the preview.
24 sample cards from the Electrical Comprehension deck
Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.
How is a resistor drawn in a UK-style circuit diagram?
A resistor is shown as a plain rectangular box (in older diagrams, a zig-zag line).
What components do an empty circle and a circle with a cross inside usually represent on a circuit diagram?
A plain circle is commonly a lamp/indicator or meter; a circle with a cross inside it represents a lamp (bulb). A circle with 'A' is an ammeter and one with 'V' is a voltmeter.
How should an ammeter and a voltmeter each be connected in a circuit?
An ammeter is connected in series (to measure the current flowing through). A voltmeter is connected in parallel across a component (to measure the potential difference across it).
What is the function of a switch in a circuit?
A switch makes or breaks the circuit, controlling whether current can flow. Closed (on) completes the path so current flows; open (off) breaks the path so no current flows.
What is the difference between an open switch and a closed switch?
An open switch leaves a gap in the circuit so no current flows. A closed switch completes the conducting path, allowing current to flow.
To switch a single lamp on or off independently while others stay on, how must the switch be wired?
It must be wired in series with that lamp only (typically on its own parallel branch), so opening it breaks only that branch.
What is the difference between a cell and a battery?
A cell is a single electrochemical unit that produces a voltage. A battery is two or more cells connected together (usually in series) to give a larger voltage or capacity.
What happens to the total voltage when identical cells are connected in series?
The voltages add up. For example, three $1.5\,\text{V}$ cells in series give $$3 \times 1.5 = 4.5\,\text{V}$$
What happens when identical cells are connected in parallel?
The voltage stays the same as a single cell, but the total capacity (and the current the battery can supply / its life) increases.
What is the difference between a primary cell and a secondary cell?
A primary cell is single-use and cannot be recharged (e.g. an alkaline AA). A secondary cell is rechargeable and can be reused many times (e.g. a lithium-ion or lead-acid battery).
What is the function of a resistor in a circuit?
A resistor opposes/limits the flow of current and is used to control current and divide voltage. It converts some electrical energy into heat.
What is the function of a capacitor?
A capacitor stores electrical charge (and energy) in an electric field between two plates, and can release it. It blocks DC once charged but passes AC, and smooths or filters signals.
What is the function of a diode?
A diode allows current to flow in one direction only (forward), blocking it in the reverse direction. It is used for rectification (converting AC to DC) and to protect circuits.
What does an LED do and what does the abbreviation stand for?
An LED (Light Emitting Diode) is a diode that emits light when current flows through it in the forward direction. It conducts in one direction only.
What is the purpose of a fuse in an electrical circuit?
A fuse is a safety device containing a thin wire that melts and breaks the circuit if the current exceeds a safe value, preventing overheating, fire and equipment damage.
How should a fuse be connected and why does it protect the circuit?
A fuse is connected in series, normally in the live wire. Because it carries the full circuit current, an excessive current melts its element and breaks the whole circuit.
What is the purpose of earthing (grounding) an appliance?
Earthing provides a low-resistance path for fault current to flow safely to ground. If a live wire touches a metal casing, the large current blows the fuse instead of leaving the case live, protecting the user from electric shock.
State the standard colours of the live, neutral and earth wires in a UK three-pin plug.
Live = brown; Neutral = blue; Earth = green-and-yellow stripes.
What does an RCD do and how does it differ from a fuse?
A Residual Current Device detects a small imbalance between live and neutral currents (indicating leakage to earth) and cuts the supply very quickly to prevent shock. A fuse only responds to excessive overall current, and more slowly.
How does the resistance of a typical filament bulb change as it heats up?
As the filament heats up, its resistance increases. A hot filament therefore has a higher resistance than a cold one, so the current is largest at the instant of switch-on.
What does adding more identical bulbs in series do to their brightness?
Adding more bulbs in series increases total resistance, reducing the current, so each bulb becomes dimmer.
What happens to the current drawn from the supply as more bulbs are added in parallel?
Each added parallel bulb provides an extra path, reducing total resistance, so the total current drawn from the supply increases (while each bulb stays at the same brightness).
What is the basic rule of magnetic poles?
Like poles repel and unlike poles attract. A magnet always has both a north and a south pole, and field lines run from north to south outside the magnet.
What is electromagnetism, and how can the strength of an electromagnet be increased?
Electromagnetism is the magnetic effect produced when current flows through a conductor; a coil of wire (solenoid) carrying current acts as a magnet. Its strength is increased by increasing the current, adding more turns of wire, or inserting a soft-iron core.
What this deck covers
The Electrical Comprehension deck follows the RAF Airman/Airwoman Selection Test (AST) Electrical Comprehension syllabus — 3 chapters and 13 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 16.7 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 160 characters, which is long enough to carry the reasoning and short enough to say out loud.
A deck like this earns its keep on the second and third pass. Read the syllabus first so you know the shape of the subject, then use the cards to find the specific facts that have not stuck.
Electrical Comprehension flashcards FAQ
How many Electrical Comprehension flashcards are in this RAF Airman/Airwoman Selection Test (AST) deck?
50 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these RAF Airman/Airwoman Selection Test (AST) flashcards free?
Yes. The preview here is free to read with no signup, and the full 50-card deck is free inside the Examius app.
What do the Electrical Comprehension cards cover?
They follow the RAF Airman/Airwoman Selection Test (AST) Electrical Comprehension syllabus — 3 chapters and 13 topics — so the questions track what is actually examinable.
How should I use these flashcards?
Read the syllabus first so you know the shape of the subject, then drill the deck. Examius schedules each card with spaced repetition, so cards you keep missing come back sooner and ones you know drift further apart.