1.

If the area of cross section of a resistance wire is halved , then its resistance becomes​

Answer»

Answer

  • R' = 2R

Given

  • The area of cross section of a resistance WIRE is halved

To Find

  • New resistance

Formula Used

\bullet \;\; \bf R=\dfrac{\rho l}{A}

Solution

For a wire having RESISTIVITY , ρ , LENGTH , l , Area of cross-section , A and Resistivity , R is ,

\bullet \;\; \rm R=\dfrac{\rho l}{A}...(1)

If the area of cross-section is halved , new Area be A' ,

  • A'  = A/2

And ALSO , new resistance be R' .

\implies \rm R'=\dfrac{\rho l}{(A')}\\\\\implies \rm R'=\dfrac{\rho l}{(\frac{A}{2})}\\\\\implies \rm R'=\dfrac{2 \rho l}{A}\\\\\implies \rm R'=2\bigg(\dfrac{\rho l}{A}\bigg)\\\\\implies \rm R'=2R\;\;[\; From\ (1)\;]

So , new resistance will doubled the old


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