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NEET2008PhysicsCurrent ElectricityActual

A wire of a certain material is stretched slowly by ten per cent. Its new resistance and specific resistance become respectively

Options

  1. A1.2 times, 1.1 times
  2. B1.21 times, same
  3. Cboth remain the same
  4. D1.1 times, 1.1 times

Correct answer

B. 1.21 times, same

Step-by-step solution

Key Idea : In stretching, specific resistance remains unchanged. After stretching, specific resistance ( ) will remain same. Original resistance of the wire, R= l A R l A or R l^2 V (as V=A l ) and R^ (l+10 % l)^2 V Therefore, R^ R = (l+ 10 100 l )^2 l^2 R^ R = ( 11 l 10 )^2 l^2 = 121 100 R^ =1.21 R

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