Kirchhoff's Laws & Measuring Instruments question from NEET 2008 (AIPMT)

Answer: (b)

1. $4\ \Omega$ and $3\ \Omega$ are in parallel between P and M: $V_{PM} = 1 \times 4 = 4\text{ V}$.
2. Lower branch: $0.5 \parallel 0.5 = 0.25\ \Omega$, plus $1\ \Omega$, total $1.25\ \Omega$ across the same 4 V.
3. Current in lower branch $= \frac{4}{1.25} = 3.2\text{ A}$
4. $V_{NM} = 3.2 \times 1 = 3.2\text{ V}$
5. So the answer is (b) 3.2 volt.