Typical ohmmeter circuit
(1) For any given ohmmeter, mid-scale deflection (one-half the maximum
defection distance) is obtained when the current through the meter is one-half the
value of the current at full-scale (zero ohms) deflection. This condition exists
when the resistance being measured is equal to the total meter circuit resistance.
Analysis of the series-type ohmmeter circuit in Figure 1-9 shows that full-scale
deflection is obtained when the meter test probe are shorted, and that less than
full-scale deflection is obtained when the resistance to be measured is connected
into the circuit.
Circuit of a series ohmeter