某條導線的半徑和長度分別是 R 和 L。另外四條以相同物料製成的導線各有如下所示的半徑和長度。四條導線中，哪條的電阻最小？

The radius and length of a wire are respectively R and L. Four other wires are made of the same material but have different radii and lengths as shown below. Which of the four wires have the smallest resistance?

某條長度為 l、直徑為d的金屬導線有 10 Ω 電阻。現有另一條以相同金屬製成的導線，它的長度是 2l 而直徑是 0.5d，求這條導線的電阻。

A metal wire of length l and diameter d has a resistance of 10 Ω. If another wire made of the same metal is 2l in length and 0.5d in diameter, what is its resistance?

兩條銅棒X和Y的半徑相同，而X的長度是Y的兩倍。求X的電阻和Y的電阻的比。

The radii of two copper rods X and Y are the same. The length of X is twice that of Y. What is the ratio of the resistance of X to that of Y?

下列哪些方法能夠增加金屬導線的電阻？

(1) 把導線繞成線圈。

(2) 把導線加熱。

(3) 把導線拉扯變長。

Which of the following methods can increase the resistance of a metal wire?

(1) Wind the wire into a coil.

(2) Heat the wire.

(3) Stretch the wire to make it longer.

一根均勻導線，直徑是 d，長度是L而電阻則是 R。如果它被另一根以相同物料製造，長度是 2L 而電阻則仍然是 R 的均勻導線所取代，後者的直徑是多少？
A uniform wire of diameter d and length L has a resistance R. It is replaced by another uniform wire of the same material but of length 2L. What should be its diameter if its resistance equals R?

如圖所示是一個長方體的金屬塊，它的尺寸是 ℓ × 2ℓ × 3ℓ。金屬的電阻率是 ρ。求金屬塊中任何兩個相對的面之間的最大電阻。
A rectangular metal block has dimensions ℓ × 2ℓ × 3ℓ as shown. The resistivity of the metal is ρ. Find the maximum resistance across any two opposite faces of the block.

家欣做實驗，研究電阻線兩端的電壓V怎樣隨通過電阻線的電流I改變。她根據實驗結果繪製了圖中的線圖。如果家欣改用同一物料、半徑相同但長度較短的電阻線重複實驗，線圖會怎樣改變（以虛線表示）？

Mary performs an experiment to find out how the voltage V across a resistance wire varies with the current I through the wire. She obtains the following graph from the experimental result. How will the graph change (indicated with a dotted line) if the experiment is repeated with a shorter wire of the same material and of equal radius?

一名學生利用圖中所示的電路，研究電阻線兩端的電壓 V 隨通過電阻線的電流 I 改變的關係，並得出圖中的 V-I 關係線圖。假如使用較幼的電阻線重複實驗。以下哪一幅線圖最能顯示新的實驗結果（以虛線表示）？已知電阻線的物料和長度維持不變。

A student sets up the circuit to investigate how the potential difference V across an eureka wire varies with the current I flowing through the wire. The result is shown in the V-I graph. If the experiment is repeated using a thinner wire of the same material and of the length, which of the following graphs (denoted by the dashed line) best shows the new result?