Physics-
General
Easy

Question

If a wire of resistance R is melted and recasted to half of its length, then the new resistance of the wire will be

  1. R/4    
  2. R/2    
  3. R    
  4. 2R    

The correct answer is: R/4


    R proportional to l to the power of 2 end exponent rightwards double arrow fraction numerator R subscript 1 end subscript over denominator R subscript 2 end subscript end fraction equals open parentheses fraction numerator l subscript 1 end subscript over denominator l subscript 2 end subscript end fraction close parentheses to the power of 2 end exponent rightwards double arrow fraction numerator R over denominator R subscript 2 end subscript end fraction equals open parentheses fraction numerator l over denominator l rightwards arrow over short leftwards arrow divided by rightwards arrow over short leftwards arrow 2 end fraction close parentheses to the power of 2 end exponent equals 4 rightwards double arrow R subscript 2 end subscript equals fraction numerator R over denominator 4 end fraction.

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