Question

Three wires A,B, C made of the same material and radius have different lengths. The graphs in the figure shows the elongation-load variation. The longest wire is:

• A. A
• B. B
• C. C
• D. All

Answer 1

Answer: (C)

C

$l=(F\times L)/(A\times Y)$
where $l$ is the elongation and other symbols have their usual meanings.
Now F is increases equally to all, so the elongation depends on Length ($L$) of wire and if length increases then elongation increases.
and in the given graph, for a particular load, elongation is maximum for wire C.
Hence it is of maximum length($L$).