Current Electricity

Two resistance of \(100 \Omega\) and \(200 \Omega\) are connected in series with a battery of \(4 \mathrm{~V}\) and negligible internal resistance. A voltmeter is used to measure voltage across \(100 \Omega\) resistance, which gives reading as \(1 \mathrm{~V}\). The resistance of voltmeter must be _______ \(\Omega\).