Question

What is angle of obliquity in mohr's circle?

Answer 1

Any plane is to be under complex stress if it has a normal and shear dtress simultaneously.
Then there will be a resultant stress. The angle between resultant and normal stress is called angle of obliquity and is represented by alpha.
A principal will have zero angle of obliquity.

Answer 2

The Angle of obliquity is defined as an angle between the normal stress and resultant stress acting on an object.

Explanation:

Whenever a body is subjected to a complex state of stress, two components called normal stress and shear stress exists. Therefore resultant stress also exists. The angle that is between resultant and normal stresses is simply the obliquity angle and is denoted by α.