國中教甄｜理化理化102 年第 32 題單選題

Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1 mm. Conductor B is a hollow tube of inside diameter 1 mm and outside diameter 2 mm. The ratio of their resistance, $R_{A} / R_{B}$ , is:

B√2

D3正確答案

答案與詳解

正確答案

R = ρL/A，材料與長度相同時電阻與截面積成反比：A 的截面積 π(0.5)²，B 的截面積 π(1² − 0.5²) 是 A 的 3 倍，故 R_A/R_B = 3。

A1✕ 錯誤

兩者截面積不同（1 : 3），電阻不會相等。

B√2✕ 錯誤

與截面積比計算結果不符。

C2✕ 易錯陷阱

D3✓ 正確

這題的完整詳解,註冊就能看 · 每天 2 題免費

精選詳解

Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1 mm. Conductor B is a hollow tube of inside diameter 1 mm and outside diameter 2 mm. The ratio of their resistance, RA​/RB​, is: