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NEET2004PhysicsCurrent ElectricityActual

The electric resistance of a certain wire of iron is R . If its length and radius are both doubled, then:

Options

  1. Athe resistance will be doubled and the specific resistance will be halved
  2. Bthe resistance will be halved and the specific resistance will remain unchanged
  3. Cthe resistance will be halved and the specific resistance will be doubled
  4. Dthe resistance and the specific resistance, both will remain unchanged

Correct answer

B. the resistance will be halved and the specific resistance will remain unchanged

Step-by-step solution

Resistance of wire R= l A Means R l A = l r^2 According to the question when l and R are doubled aligned & R₁ 2 l (2 r)^2 & R₁ 1 2 R aligned Here specific resistance of wire is independent of geometry wire so it depends on the material of wire.

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