Question

which of the following micrometers is unique in the way that the observer reads the results?
outside micrometer
hub micrometer
blade micrometer
depth micrometer

Explanation:

Outside, hub, and blade micrometers measure linear dimensions in a relatively similar way based on the alignment of main - scale and thimble - scale markings for external or specific part features. A depth micrometer, however, measures depth, and its reading involves understanding the zero - setting and the position of the spindle relative to the reference surface in a way that is distinct from the others in terms of the orientation and the nature of the measurement being depth rather than a simple external or part - feature dimension.

Answer:

Depth micrometer