1.
What is a topographic map? How is an AFM image that you obtained using the Excel
spreadsheet like a topographic map?
Solution
Topographic maps can be defined as accurate graphic representations of features present on the
surface of earth. The features represented are roads, buildings, railways, airports, lakes, rivers,
streams, swamps, mountains, valleys etc. On a topographical map, features having same height
are joined together by a line known as contour line.
Similarly, in atomic force microscopy (AFM), the signals are recorded when a bump is
encountered by the pointer. The height of the bump determines the force experienced by the
pointer and hence the strength of the signal for that particular bump. This means that all the
bumps on the surface with same height will give same signal in AFM, and in this way, AFM
image and topographical maps are similar.