Question

What value of angle Φ is between the plate and cone in Cone-and-Plate viscometer?

(a) More than 3°

(b) Less than 3°

(c) More than 2°

(d) More than 5°

I had been asked this question during a job interview.

This intriguing question comes from Viscosity Measurement in section Fluid Flow and Mixing of Bioprocess Engineering

Answer 1

Right answer is (b) Less than 3°

Best explanation: The angle Φ between the plate and cone is very small, usually less than 3°, and the fluid to be measured is located in this small gap. Large cone angles are not used for routine work for a variety of reasons, the most important being that analysis of the results for non-Newtonian fluids would be complex or impossible.