Physics 9702 · AS & A Level · Potential difference and power

Potential difference and power — practice question

A power cable $X$ has resistance $R$ and carries current $I$. A second cable $Y$ has resistance $2R$ and carries current $\frac{1}{2}I$. What is the ratio $\dfrac{\text{power dissipated in }Y}{\text{power dissipated in }X}$?

  • A$\frac{1}{4}$
  • B$\frac{1}{2}$
  • C$2$
  • D$4$

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