A square area (on the surface of the earth) with side 100 m and uniform height, appears as 1 cm2 on a vertical aerial photograph

Q. A square area (on the surface of the earth) with side 100 m and uniform height, appears as 1 cm² on a vertical aerial photograph. The topographic map shows that a contour of 650 m passes through the area. If focal length of the camera lens is 150 mm, the height from which the aerial photograph was taken, is

(A) 800 m                      (B) 1500 m                    (C) 2150 m                    (D) 3150 m

Ans: 2150 m  

Sol:

Actual area = 100×100=10⁴m²

Area on the map = 1 cm2 = 10⁻⁴ m²

Elevation of the surface = 650 m

The focal length of the camera, f = 150 mm

Scale of the photograph,