This viscometer is composed of two balls of equal diameter and equal mass, which are hung on the two arms of a balance whose ratio of arms
LB and
LA is ν. The liquid to be measured is put in two vessels, in which the balls are immersed. Each vessel is drawn up with desired constant velocities of υ
A and υ
B, such that their ratio becomes υ
B/υ
A=
n=_??_.
By adjusting a counter weight
W, hung on the arm at the position of
L from the fulcrum, the balance is brought into equilibrium.
Let the weight
W at υ
A=υ
B=0 be
W0, the difference
ΔW of the weights
W0 and
W, gives the viscosity η by the equation η=
n/1-
n•1/6πr•
L/
LA•
ΔWg/υ
A, assuming Stokes' law of viscosity.
Moreover, the viscosity η can be obtained independently of the lifting velocity, provided that the lifting velocity is small.
The results of experiments show that the true value of the viscosity is obtainable by direct indication.
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