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When the length of a wire is doubled, the ammeter reading reduces to _____.
Aone-fourth
Bone
Chalf
Dthree-fourths
Answer & Solution
Correct answer: C. half
1. Resistance is directly proportional to length, so doubling length doubles resistance.
2. By Ohm's law I = V/R, doubling R at constant V halves the current.
3. Hence the ammeter reading reduces to half.
_Source: RRB Group D CEN-02/2018 PYQ, Q.54._
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