🔍 Key Concepts

• Ohm’s Law and the basic formula for resistance of a wire or bar-shaped conductor • The relationship between length, cross‑sectional area, and resistivity in determining resistance • How temperature affects the resistance of most metallic conductors used on vessels

💭 Think About

• Recall the standard formula used in electricity for calculating the resistance of a uniform conductor. Which physical dimensions of the conductor appear in that formula? • Think about what happens to a long, thin wire versus a short, thick cable made of the same metal. How does each one conduct current? • When shipboard wiring heats up under load, what typically happens to its resistance—does it stay the same, increase, or decrease?

✅ Before You Answer

• Write down or recall the resistance formula that includes length and area: does each of these increase or decrease resistance? • Consider if temperature is assumed constant in basic formulas, and what is commonly taught about resistance of metals as temperature rises. • Before choosing, ask: is there more than one factor in the list that clearly affects resistance according to your basic electrical theory?