D43 QUIZ OF THE DAY

Assertion (A): Fore bearing and back bearing of a line differ by 180°. Reason (R): Local attraction does not affect the difference in FB and BB.

• Both A and R are true and R is the correct explanation of A
• Both A and R are true but R is not the correct explanation of A
• A is true but R is false
• A is false but R is true

Answer explanation

Local attraction affects the difference in FB and BB; hence R is false.

Which of the following statements are true regarding magnetic declination? I. It is the angle between true and magnetic meridian II. Declination is zero when both meridians coincide

• Only I is correct
• Only II is correct
• Both I and II are correct
• Neither I nor II is correct

Answer explanation

Magnetic declination is the angle between magnetic and true meridian. If both coincide, it becomes zero.

Match the compass parts with their function: A. Agate Cap B. Magnetic Needle C. Prism D. Graduated Ring

1.indicates N-S prism

2.Pivot support

3.Reading aid

4.Measures angle

• A-2, B-1, C-3, D-4
• A-3, B-1, C-2, D-4
• A-4, B-2, C-1, D-3
• A-1, B-3, C-4, D-2

Answer explanation

Correct matches: Agate Cap – Pivot support, Magnetic Needle – Indicates N-S, Prism – Reading aid, Graduated Ring – Measures angle

A line AB is 100 m long and has a bearing of 30°. Calculate its latitude.

• 86.6 m
• 50.0 m
• 43.3 m
• 100.0 m

Answer explanation

Latitude = 100 × cos(30°) = 86.6 m

A line AB is 80 m long and has a bearing of 60°. Calculate its departure.

• 69.3 m
• 46.2 m
• 40.0 m
• 55.0 m

Answer explanation

Departure = 80 × sin(60°) ≈ 69.3 m

Back bearing of a line is equal to fore bearing ± ___?

• 90°
• 180°
• 270°
• 360°

Answer explanation

BB = FB ± 180° is a rule for computing back bearing.

What is the least count of a prismatic compass?

• 15 minutes
• 30 minutes
• 1 degree
• 45 minutes

Answer explanation

The least count of a prismatic compass is 30 minutes.

Which type of alidade is suitable for long and inclined sights?

• Plain alidade
• Beveled alidade
• Telescopic alidade
• Ranging alidade

Answer explanation

Telescopic alidade is suitable for long inclined sights.

The process of establishing the instrument station on the sheet is known as:

• Centering
• Orientation
• Levelling
• Sighting

Answer explanation

Centering refers to aligning the instrument above the ground point.

In prismatic compass, 0° is marked at which direction?

• North
• East
• South
• West

Answer explanation

In prismatic compass, 0° is at South, 90° at West, 180° at North.