Power dissipation via Joule's law

Steps:

• Convert resistance: 25 mΩ = 0.025 Ω.
• Apply formula P = I²R, where I = 35 A.
• Calculate I² = 35 × 35 = 1225.
• Compute P = 1225 × 0.025 = 30.625 W ≈ 31 W.

Why A is correct:

• Joule's law states power dissipated in a wire is P = I²R; substituting values gives exactly 31 W (rounded).

Why the others are wrong:

• B: Incorrectly uses 0.25 Ω instead of 0.025 Ω, yielding 306 W (not 49 W).
• C: Likely confuses with heater power or uses wrong formula like P = V²/R without voltage.
• D: Gross error, perhaps treating resistance as 25 Ω and adding extraneous factors.

Final answer: A