Question

A current of ${10}^{-3}A$ is flowing in a resistance of $1000\Omega$. To measure potential difference accurately, a voltmeter should be used, which has resistance of

• A. $0\Omega$
• B. $500\Omega$
• C. $1000\Omega$
• D. $>>1000\Omega$

Answer 1

The correct option is D $>>1000\Omega$

if voltmeter's resistance is comparable or lesser than $1000\Omega$ then the potential difference shown by voltmeter will not be the actual potential difference across the resistor.
This is because significant part of current which is flowing through the resistor will go in the branch containing the voltmeter if, the resistance of the voltmeter is not very high than $1000\Omega$.
Therefore, option(D)