Question

The combined correction due to curvature and refraction is given by __________ (where d is in km)

1. 0.095 d2
2. 0.01122 d2
3. 0.06735 d2
4. 0.572 d2

Answer 1

Correct Answer - Option 3 : 0.06735 d2

Concept:

Curvature Correction:

The curvature correction is given by:

\({C_C} = - \frac{{{d^2}}}{{2R}}\) = - 0.0785 d²

where

d = distance between any two given points (in km)

R = Radius of Earth = 6370 km

The curvature correction is always negative.

Refraction Correction:

The refraction correction is given by:

\({C_R} = \frac{1}{7} \times \frac{{{d^2}}}{{2R}}\) = + 0.0112 d²

The refraction correction is always positive.

Combined Correction due to curvature and refraction:

The combined correction due to curvature and refraction is given by:

C = – 0.0785 d2 + 0.0112 d2

C = – 0.0673 d2