Science (086) — CBSE Class 10 board question

Step 1: Find total resistance (series circuit)

$$R_s = 1\,\Omega + 2\,\Omega = 3\,\Omega$$

Step 2: Find current in the circuit

$$I = \frac{V}{R_s} = \frac{6\,\text{V}}{3\,\Omega} = 2\,\text{A}$$

Step 3: Find power consumed in the 2 Ω resistor

$$P = I^2 R = (2)^2 \times 2 = 4 \times 2 = \boxed{8\,\text{W}}$$

Source: Chapter 11, Section 11.8 Electric Power; Section 11.6.1 Resistors in Series

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• Since it is a series circuit, the same current flows through both resistors. Find total resistance first, then current using Ohm's law, then apply $P = I^2R$ to the specific resistor (2 Ω only, not total).
• Examiners award marks for each step: total R, current I, and final power. Show all three steps clearly.
• Do not use total voltage (6 V) directly in $P = V^2/R$ unless you first find the voltage across the 2 Ω resistor alone ($V_2 = 2\times2 = 4$ V → $P = 16/2 = 8$ W — same answer, but the $I^2R$ method is more straightforward here).