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QAIPMT-2004-Ph-2621: NEET 2004 Physics - Class 12 AIPMT-2004-Ph-2621 Solution: The electric resistance of a certain wire of iron is R. If its…
The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then
Multiple Choice Options
- A The resistance will be doubled and the specific resistance will be halved.
- B The resistance will be halved and the specific resistance will remain unchanged.
- C The resistance will be halved and the specific resistance will be doubled.
- D The resistance and the specific resistance, will both remain unchanged.
Step-by-Step Verified Solution
Resistance of wire = _ l A
R _ l A = l � r 2
When length and radius are both doubled
R 1 _ 2 l � ( 2 r ) 2 _ R 1 _ 1 2 R
The specific resistance of wire is independent of geometry of the wire, it only depends on the material of the wire.