Avielevate / DGCA CPL papers / Air Navigation / Magnetism & Compass
Magnetism & Compass — DGCA CPL Air Navigation
Chapter GN08 of the Air Navigation paper. 100 practice questions in the Avielevate bank, every one with its answer key, filterable into a timed set on this chapter alone.
What this chapter covers
The learning objectives we file Magnetism & Compass questions under, and how many sit behind each. These come straight out of the bank and are regenerated whenever it changes — they are what is there today, not a claim.
| Learning objective | In the bank |
|---|
| __GEN__ General | 100 questions |
Sample Magnetism & Compass questions, answered and explained
Real questions from this chapter, with the answer marked and the reasoning written out — the same explanations you get inside the app.
0216104 · Magnetism & Compass
The total magnetic field T is 50 microtesla (µT) and the dip angle is 60°. What are the horizontal component H and the vertical component Z?
- AH = 25 µT, Z = 43.3 µT
- BH = 43.3 µT, Z = 25 µT
- CH = 30 µT, Z = 40 µT
Why that is the answer
The Earth's magnetic field at a place points along a slanting line, the **total field (T)**. It can be split into a **horizontal component (H)**, the part that turns a compass, and a **vertical component (Z)**, the part that pulls the needle downwards. The angle of T below the horizontal is the **dip (θ)**.
Look at the diagram: T is the long sloping side of a right-angled triangle, H is the side next to the dip angle, and Z is the side opposite it. So H = T × cos θ and Z = T × sin θ.
Apply it, with T = 50 µT and dip 60°:
H = 50 × cos 60° = 50 × 0.5 = **25 µT**
Z = 50 × sin 60° = 50 × 0.866 = **43.3 µT**
The dip is steep (60°), so it makes sense that the vertical part is bigger than the horizontal part.
So **H = 25 µT and Z = 43.3 µT**.
0216198 · Magnetism & Compass
During a sustained turn ____ the nearer magnetic pole, the effect of liquid swirl will ____ the compass turning error.
- Atowards; not affect
- Btowards; increase
- Caway from; not affect
Why that is the answer
In a banked turn the compass magnet tilts with the aircraft, and the vertical part of the Earth's field drags it sideways. This **turning error** is largest when turning through north or south (look at the diagram).
When turning towards the **nearer magnetic pole** (through north in the northern hemisphere, through south in the southern), the magnet is dragged round **in the same direction as the turn**, so the compass lags behind the real heading.
The liquid in the compass bowl is also carried round with the bowl, so it swirls in the direction of the turn. In a long, sustained turn this moving liquid drags the magnet even further the same way, making the lag worse.
So in a sustained turn **towards** the nearer magnetic pole, liquid swirl will **increase** the compass turning error.
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Frequently asked
How many Magnetism & Compass questions are there for the DGCA CPL Air Navigation paper?
Avielevate's bank carries 100 published Magnetism & Compass questions for Air Navigation, mapped across 1 learning objective. Every one has its answer key, and explanations are being written across the whole bank.
How much of the Air Navigation paper is Magnetism & Compass?
The DGCA does not publish a per-chapter breakdown of its papers, so nobody can honestly tell you — and we will not guess. What we can tell you is what students who have just sat a paper reported meeting, which is measured rather than rumoured: that is the exam recall report inside the app.
What is the best way to revise Magnetism & Compass?
Sit a short timed set on this chapter alone, tag how sure you were of each answer, then drill the two that actually leak marks: the ones you got right while guessing, and the ones you got wrong while confident. Avielevate does that tagging for you and puts anything you got wrong back in front of you on a spaced schedule.
The rest of the Air Navigation paper
One account covers every chapter of every paper.
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