Question

find the new resistance of a wire whose length is decreased to one third of its original length where initial resistance is 10 ohm??​

Answer 1

Answer:

I will give only model of the sum

we know ,

if wire is stretched by ‘n′ times it's resistance increases by  n2  times because,

R∝lA and if ‘l’ increased by ‘n’ times then simultaneously ‘A’ is automatically decreased by same factor ’n’ to maintain constant volume of wire

in your question increasing length by 10% means increasing wire length by  1.10  times which will result in increased resistance by  (1.10)2=1.21  times

so if older resistance was  10Ω  then new resistance will be  12.1Ω  

note : resistance increases by 21% if wire is stretched by 10%

Explanation: