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NEET2009PhysicsCurrent ElectricityActual

For a metallic wire, the ratio V i ( V= applied potential difference and i= current flowing) is

Options

  1. Aindependent of temperature
  2. Bincreases as the temperature rises
  3. Cdecreases as the temperature rises
  4. Dincreases or decreases as temperature rises depending upon the metal

Correct answer

B. increases as the temperature rises

Step-by-step solution

The resistance of a metallic wire at temperature t^ C is given by R_t=R₀(1+ t) where is coefficient of expansion. Hence, resistance of wire increases on increasing the temperature. Also, from Ohm's law, ratio of V i is equal to R ie, V i =R Hence, on increasing the temperature the ratio V i increases.

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