A 1m long metallic wire is broken into two unequal parts A and B. The part A is uniformly extended into another wire C. The length of C is twice the length of A and resistance of C is equal to that of B. The ratio of resistances of parts A and C is
A
4
B
C
2
D
Text Solution
Verified by ExpertsThe correct answer is:
B
let L A and L B be length of parts A and B
Then 
= 
[as cross-section is same]
Now L c = 2 L A and (volume) c = (volume) P
i.e. L c × A c = 2 L A × A c = L A × A A
where A c = A A are cross-sectional area of part C and A.
∴ A c = A A /2
= 
= 
× 
= 
× 
= 
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