Electrical Power & Heating Effect question from NEET 2008 (AIPMT)

Answer: (b)

1. The $2\ \Omega$ branch and the $(1 + 5)\ \Omega$ branch are in parallel.
2. Voltage across them: $V = 3 \times 2 = 6\text{ V}$.
3. Current in the $6\ \Omega$ branch: $I = 6/6 = 1\text{ A}$.
4. $P_5 = I^2 R = 1^2 \times 5 = 5\text{ W}$, so the answer is (b) 5 watt.