Power dissipation in internal resistance

Steps:

• Calculate total resistance: 4.7 Ω + 9.3 Ω = 14.0 Ω.
• Find current: I = emf / total resistance = 3.0 V / 14.0 Ω ≈ 0.214 A.
• Compute power in internal resistance: P = I² × 4.7 Ω ≈ (0.214)² × 4.7 ≈ 0.22 W.

Why A is correct:

• Power P = I²r follows Joule's law, where I is circuit current and r is internal resistance.

Why the others are wrong:

• B: Uses lamp resistance alone for power, ignoring internal drop.
• C: Approximates total power without isolating internal component.
• D: Assumes full emf across internal resistance, neglecting lamp.

Final answer: A