Two wires are made of the same material and have the same length, but one is thicker than the other. Which wi…

Question

Two wires are made of the same material and have the same length, but one is thicker than the other. Which wire has greater resistance, and why?

Accepted Answer

## Model Answer The **thinner wire** has greater resistance. According to the formula $R = \rho \dfrac{l}{A}$, resistance is **inversely proportional to the area of cross-section** (A). A thicker wire has a larger cross-sectional area, so its resistance is lower. The thinner wire has a smaller area, giving it greater resistance, even though both wires have the same length and material. *Source: Chapter 11, Section 11.5 – Factors on which the resistance of a conductor depends* --- ## Explanation - Examiners expect you to state **which** wire clearly, then justify using the formula $R = \rho l/A$. - Key point: same material → same ρ; same length → l is equal; only A differs. So resistance depends solely on cross-section here. - "Thicker" means larger diameter → larger A → smaller R. Don't confuse thicker with higher resistance. - Always write the formula and link it to the concept for full 2-mark credit.

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