Heyy mates!!!
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Find the percentage change in resistance when wire of length 'L' and area of cross section 'A' is recast to make length n times.
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Answers
Answer:
But resistance is also inversely proportional to the area of cross-section, and as area of cross-section is halved due to doubling of length, the resistance is once more doubled due to the halfing of the area of cross-section. So overall the resistance of the wire becomes four times the original resistance.
Explanation:
We have ,
R1 = rho L/A
Since , length increased by n times→ new length = n L
We know that area is inversely proportional to length
→New area = A/n
New , resistance R2 = rho nL/(A/n)
= n^2 rho L/A
= n^2 R1. {using ( 1)}
→Change in resistance =R2-R1
=R1(n^2-1)
Hence , percentage change in resistance
=(Change in resistance )×100/R1
= R1(n^2-1)100/R1
=(n^2-1)100 percent
Hey mate this is ur answer but for ur convenience these types of questions are not asked in CBSE 10th board ......