What is voltmeter sensitivity?

Answer 1

Voltmeters are connected in parallel with the components whose voltage or voltage drop you want to measure. That means that the internal voltmeter's resistance will create a new branch in parallel with the component, thus increasing the current in the circuit.

If there are other components in series with the component to which the voltmeter is connected, this increment of current will increase the voltage drop across them, reducing the voltage drop across the component whose voltage is being measured. This is obviously an induced error in the measurement, which adds up to other errors built into the voltmeter (accuracy, resolution, linearity, parallax, etc.)

When measuring the output voltage of low resistance (high current) power supplies, the input impedance is usually not an issue. However, when measuring a low current power supply, the input resistance of the voltmeter will have to be at least 10 times the internal resistance of the power supply. Otherwise, the error will be too noticeable.

Therefore, the ideal voltmeter should have an infinite internal resistance. Since this is not the case, it should at least have several megohms.

Analog voltmeters usually have s sensitivity of 20 to 30 kilohm per volt (kΩ/V), which varies withe the voltmeter range setting.

Digital voltmeters, instead, have constant high (>20 megohms) input impedance, which is a combination of pure resistance and reactance, usually capacitive, regardless of the voltage range. That is why the specs of a digital voltmeter always indicate the input capacitance.

Answer 2

A voltmeter is said to be sensitive when it shows a greater deflection for a small amount of P.D. There two kinds of meter analog and digital. neither is better then the other it all depends on the applications sensitivity is related to what value of input will register a reading from the meter. Which is related to the scale of sensitivity as set by a either automatic or mechanical switch