Physics 9702 · AS & A Level · Resistance and resistivity

Resistance and resistivity — practice question

A wire used in a heating element has resistance $R$. It snaps and is then swapped for another wire. The table lists the data for the original wire and the new wire. For the original wire, the length is $l$, the diameter is $d$ and the resistivity is $\rho$. For the new wire, the length is $l$, the diameter is $2d$ and the resistivity is $2\rho$. What is the resistance of the new wire?

  • A$\frac{R}{4}$
  • B$\frac{R}{2}$
  • C$R$
  • D$2R$

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