Wire gauge matches current load

Steps:

• Identify currents: Starter motor draws high current (hundreds of amps) to crank engine; ignition switch handles low current (few amps) for control signals.
• Recall wire properties: Resistance R = ρL/A; thicker wires (larger A) reduce R, minimizing voltage drop and heat for high currents.
• Compare circuits: Long, thin wires suit low-current ignition path; short, thick wires suit high-current starter path to avoid excessive power loss.
• Conclude: Wire choice prevents overheating and ensures efficient operation based on current differences.

Why D is correct:

• Ohm's law (V=IR) and power loss (P=I²R) require low-resistance thick wires for high-current starter circuits, while low-current ignition allows thin wires.

Why the others are wrong:

• A: Thicker wires have lower resistance, so they heat up less, not more.
• B: Thin wires have higher resistance due to smaller cross-section.
• C: While similar, it incorrectly focuses on entire circuits rather than components; starter circuit current is high at the motor, but ignition switch specifically carries low current.

Final answer: D