JEE MainPhysicsCurrent ElectricityMCQ+4 / −1
A wire of resistance is melted and drawn in a wire of one-fourth of its length. The new resistance of the wire will be
- A
- B
- C
- D
View written solutionFree
Correct answer: D
-
Use the resistance formula
For a wire, where is resistivity, is length, and is cross-sectional area.
-
Apply conservation of volume
When the wire is melted and redrawn, its material and hence its volume remain the same:
Given the new length is one-fourth of the original:
So,
-
Find the new resistance
The new resistance is
-
Substitute the original resistance
-
Match with the options
Therefore, the new resistance is:
So the correct option is D.
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