Question

An aerial photograph is taken from a flight at a height of 3.5 km above mean sea level, using a camera of focal length 152 mm. If the average ground elevation is 460 m above mean sea level, then the scale of the photograph is

• A. 1 : 20000
• B. 1 : 20
• C. 1 : 100000
• D. 1 : 2800

Hint:

The scale of an aerial photograph is the ratio of the camera's focal length to the adjusted height of the camera above the ground.

Answer 1

The Correct Option is A

The scale of an aerial photograph is given by the ratio of the focal length to the height of the camera above the ground. The formula for the scale is: \[ \text{Scale} = \frac{f}{H} \] where: - \( f \) is the focal length of the camera (152 mm), - \( H \) is the height of the camera above the ground, which is 3500 m - 460 m = 3040 m (adjusted for the ground elevation). Thus, the scale is: \[ \text{Scale} = \frac{152 \text{ mm}}{3040 \text{ m}} = \frac{152}{3040000} = 1 : 20000. \] So, the correct scale of the photograph is 1 : 20000, corresponding to option (A).