Q21 of 330 Page 26

How does the resistance of a wire vary with its :

(a) area of cross-section?


(b) diameter?

(a) The resistance of a metal wire is inversely proportional to the area of the wire, so if the area increase resistance decrease.

(b) If diameter increase than area increase and the resistance decreases.


More from this chapter

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19

Calculate the resistance of an aluminium cable of length 10 km and diameter 2.0 mm if the resistivity of aluminium is 2.7 x 10-8Ωm.

 20

What would be the effect on the resistance of a metal wire of :

(a) increasing its length?


(b) increasing its diameter?


(c) increasing its temperature?

 22

How does the resistance of a wire change when:

(i) its length is tripled?


(ii) its diameter is tripled?


(iii) its material is changed to one whose resistivity is three times?

 23

Calculate the area of cross section of a wire if its length is 1.0 m, its resistance is 23Ω and the resistivity of the material of the wire is 1.84 x 10-6 Ωm.