Question
Thu April 03, 2014 By: Prajjawal Banati

A wire has resistance equal to R. Then it was stretched to twice it's original Length. Calculate the increse in resistance?

 

Sir in some answers of this question they have taken new length as 3l and in some 2l.Please remove this confusion of mine.

 

 

Expert Reply
Sat April 05, 2014
Let l be the initial length and r be the initial radius of wire.
Let l1 be the length and r1 be the radius after stretching.
l1 = 2 l
On stretching the wire to twice its initial length the resistance becomes 4 R,four times the initial resistance
Stetching the wire to twice its initial length means ,new length= 2 times initial length.
amd not 3 times initial length.
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