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Solution


Q.

The resistance of the wire when the length of the wire increases two times:
1 becomes 2 times  
2 becomes 3 times  
3 becomes 6 times  
4 becomes 4 times  

Ans.

 (1)

The electrical resistance of a wire can be expressed as:R=ρLA

Where, A = Area of cross-section of the conductor, L = Length of the conductor, ρ = Resistivity

From this relation, it is clear that the resistance is directly proportional to the length and inversely proportional to area of cross-section.

If length becomes 2L, then

R'=ρ2LA=2ρLASo, R' = 2R

Thus, the resistance becomes 2 times if the length of the wire is doubled.