The value of magnetic declination, if the magnetic bearing of sun at noon is 350° is
- A10° ECorrect
- B10° W
- C80° E
- D80° W
Solution
Concept
Magnetic declination from an observation of the sun
Formula
Declination = True bearing − Magnetic bearing (east if positive)
Step-by-step solution
1. The sun at noon lies on the meridian, so its true bearing is 0° (360°) when seen towards the north. 2. Magnetic bearing observed = 350°. 3. Declination = 360° − 350° = 10°. True bearing is greater, so the declination is East.
Explanation
The true bearing of the sun at noon is 0° (the sun is on the meridian). The magnetic bearing observed is 350°, so magnetic north lies 10° east of true north: declination = 10° E.
Shortcut
Declination (E) = TB − MB.
Common mistake
Taking the true bearing as 180° and getting a large difference.
Correct answer: A) 10° E