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When a wire is compressed and it's radius becomes 2R then it's resistance will be:

Correct answer: C. 1 / 16 R

  • A. 16R
  • B. 4 R
  • C. 1 / 16 R
  • D. 1 / 4 R

Explanation

Taking volume constant... A- Cross sectional area of wire (pi x r^2) L-Length of wire. A2.L2=A1.L1 r2=2r1; as it is written that diameter is doubled. So A2=4A (as r^2 goes in the formula.) If the radius is doubled length becomes ¼ ,resistance is proportional to L/A Thus, R2=R1/16

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