A voltmeter having a resistance of $998\Omega$ is connected to a cell of emf 2 V and internal resistance $2\Omega$. The error in the measurement of emf will be

Error in measurement - Actual value Measured value

Actual value = 2V 

$\begin{array}{l}\mathrm{i}=\frac{2}{998+2}=\frac{1}{500}\mathrm{A}\\ \mathrm{Since}\mathrm{E}=\mathrm{V}+\mathrm{ir}\Rightarrow \mathrm{V}=\mathrm{E}-\mathrm{ir}=2-\frac{1}{500}\times 2=\frac{998}{500}\mathrm{V}\\ \therefore \mathrm{Measured}\mathrm{value}=\frac{998}{500}\mathrm{V}\\ \Rightarrow \mathrm{Error}=2-\frac{998}{500}=4\times {10}^{-3}\mathrm{V}\end{array}$