The voltmeter reads 40 V across  resistance. The resistance of voltmeter is ………. Ohm

 

$$\begin{gathered} Voltmeter and 60\Omega are in parallel , hence will have same potential of 40 V. \\ \therefore Battery will supply 40 V to 20\Omega resistor. \\ Apply ohm\text{'}s law \\ \text{i\hspace{0.17em}\hspace{0.17em}=\hspace{0.17em}}\frac{40}{20}=2\text{\hspace{0.17em}A} \\ {\text{i}}_{\text{1}}\text{=\hspace{0.17em}}\frac{40}{60}=\frac{2}{3}\text{\hspace{0.17em}A} \\ {\text{i}}_{\text{2}}={\text{\hspace{0.17em}i\hspace{0.17em}-\hspace{0.17em}i}}_{\text{1}}=2-\frac{2}{3}=\frac{4}{3}\text{A} \\ {\text{i}}_{\text{2}}{\text{R}}_{\text{V}}=40 \\ \Rightarrow \frac{4}{3}{\text{R}}_{\text{V}}=40 \\ \therefore {\text{\hspace{0.17em}R}}_{\text{V}}=30\Omega \end{gathered}$$