Q.A voltmeter has a resistance of 100 \Omega. What will be its reading when it is connected across a cell of emf 2 V and internal resistance 20 \Omega?

[!TLDR] With the 100 \Omega voltmeter and 20 \Omega internal resistance in series, I=2/120A, so the voltmeter reads 100×2/120≈1.67V …

A voltmeter of resistance 100 \Omega is connected across a cell of emf 2 V and internal resistance 20 \Omega. As in Numericals 12, the voltmeter itself completes the loop, so the current is

and the voltmeter reads

$V = IR_V = 0.01667\times100 \approx 1.667\ \text{V}$ …

Treat the voltmeter's resistance as the sole external load in series with the cell's internal resistance, …

Rounding intermediate steps too early (e.g. rounding the current before multiplying by $R_V$), which can shift the final a …