Example:    An ohm meter has a meter movement along with a 100 µA full-scale deflection.  An open circuit voltage at terminals ab is 24 V.  An ohm meter is zeroed and then an unknown resistance R_x is measured, that generates quarter-scale deflection. Find R_x.

Solution:

First find R_o.

R_o = V/I_m

= 24/1 x 10^-6

R_o = 2.4 x 10⁵? or 240K?

Then solve for R_x:

R_x = (1-D/D)R_o

=((1-1/4)/(1/4))(240)

=(3)(240)

R_x= 720 K?

Thus, quarter scale deflection of this ohm meter face would read 720 K.