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GATE 2023 CE (CE2) – Question 24

Geomatics Engineering · Distance and angle measurement, levelling, traversing, triangulation, total station · 1 mark · Multiple choice

The magnetic bearing of the sun for a location at noon is 183° 30′. If the sun is exactly on the geographic meridian at noon, the magnetic declination of the location is ______.

  1. 3° 30′ W
  2. 3° 30′ E
  3. 93° 30′ W
  4. 93° 30′ E

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Show answer and explanation

Correct answer: (A) 3° 30′ W

Explanation

**Step 1: true bearing of the sun at noon.** At local noon the sun is exactly on the geographic meridian, due south for a place in the northern hemisphere, so its true bearing is $180^\circ$.

**Step 2: declination.**
$$\text{declination}=\text{true bearing}-\text{magnetic bearing}=180^\circ-183^\circ30^\prime=-3^\circ30^\prime .$$

A negative value means the magnetic north is to the **west** of true north.

Declination $=\mathbf{3^\circ30^\prime\ W}$ (option A).

Official GATE 2023 answer key: https://gate2026.iitg.ac.in/doc/download/Answer_keys2023/CE2_ANS_GATE2023.pdf