Question

If internal circuit of voltmeter is open circuit then how can it measure the voltage quora

Answer 1

Answer:

HI FRIEND

Explanation:

Mathematically speaking ,An open electrical circuit is the circuit  where current = 0 .  

But yes if there is a paralell branch consisting of any  resistor of something like that The voltage across the open end will be given by the voltage across that branch .

Like you see in the above figure . If you open circuit the resistor R3  branch That will be an open circuit . but it will give you the voltage drop if you connect voltmetre across 4-5 brach . That voltage will be the drop across resistor R2 .  

while in another case if you open all the three resistors and measaure across 2-7 it will give you the voltage across the power source .  

Hence if the circuit is open current will be zero and voltage will be something .So yes voltmetre will show some voltage reading if the voltage source is connected but if you are putting a dependent source of current source . The scenario will be compleately diff.