Voltmeter sensitivity is determined by its ohms per volt rating, with higher ratings indicating higher sensitivity. When connecting a voltmeter across a highly resistive circuit, it can lower the equivalent resistance as it acts as a shunt, resulting in a lower displayed voltage than the actual value. This "loading effect" can be avoided by using a high sensitivity voltmeter with a high ohms per volt rating.

1. VOLTMETER SENSITIVITY

2. VOLTMETER SENSITIVITY
 OHMS PER VOLT RATING
 LOADING EFFECT

3. OHMS PER VOLT RATING

4. Loading effect
 A voltmeter when connected across
two points in a highly resistive circuit,
acts as a shunt for that portion of the
circuit and thus reduces the equivalent
resistance in that portion of the circuit.
The meter will then give a lower
indication of the voltage drop than
actually existed before the meter was
connected. This effect is called as
loading effect.

5.  To avoid loading effect use high
sensitivity voltmeter.
 Refer class notes for problems