Three voltmeters, all having different internal resistances are joined as shown in figure. When some potential difference is applied across A and B, their readings are V₁, V₂ and V₃. Choose the correct option.

Solution

Physics sir · 4 steps

A voltmeter reads the potential difference across its own two ends, whatever its resistance is.

1. Read the circuit. V₁ and V₂ are in series on the upper branch. V₃ sits alone on the lower branch. Both branches join the same two points, A and B.
2. Series branch. On the upper branch, the drop from A to B is the sum of the drops across the two meters. Their resistances only decide how that total is split between them.
3. Parallel branch. V₃ is connected straight across A and B, so it reads the full V_A - V_B. Parallel branches always have the same potential difference across them.

   V₁ + V₂ = V_A - V_B = V₃

4. So. V₁ + V₂ = V₃ holds for any internal resistances, which is option (c).

The idea to keep. Different meter resistances change how the voltage is shared within a branch, never the total. Drops along a series path add up to the drop across any parallel path between the same two points.

Answer from the NTA final answer key. Solution by PrepWiser.