Remote Sensing

The formula for the ground swath width of the scene, given the field of view (FOV) and nadir height , is: Given: -
-
Substitute the values into the formula: Thus, the ground swath width of the scene is 12 km.

The Earth spins around its axis, and when viewed from the North pole, the rotation of the Earth appears to be in an anti-clockwise direction. This rotation is from West to East. The Earth rotates in a counter-clockwise direction (when viewed from above the North pole), causing the Sun to rise in the East and set in the West. Explanation of the Direction:
- The Earth's rotation is actually west to east. However, when viewed from the North pole, this motion appears to be in the anti-clockwise direction.
- This is consistent with the way we observe daily events, such as the rising and setting of the sun, which is due to the Earth's rotation.
Thus, the correct answer is (A), as the Earth appears to rotate in a west to east direction in an anti-clockwise manner when viewed from the North pole.

The scale of the Survey of India topographic sheet is given as , which typically refers to the scale of the map. For Survey of India maps, this scale is usually 1:50,000.
A 4 degree by 4 degree area is the area that needs to be covered. The total area covered by one toposheet depends on the scale. To find the number of toposheets required to cover an area of 4° by 4°, we need to calculate the total number of toposheets needed based on the scale.
First, the total area of 4° by 4° on the ground corresponds to: Since the topographic map covers a smaller area, we calculate how many of these areas fit into the larger 4° by 4° area: Now, for each toposheet, which covers an area of 1° by 1° (or 12321 sq. km), the number of toposheets required is: Thus, the number of toposheets required to cover a land area equivalent to 4 degree by 4 degree is 256.