Physics 9702 · AS & A Level · Potential dividers

Potential dividers — practice question

For the circuit diagram shown, XY is a length $L$ of uniform resistance wire. A potential difference is applied across XY. $R_1$ and $R_2$ are unknown resistors. J is a sliding contact that connects the junction of $R_1$ and $R_2$ to positions on XY through a lamp S. J is shifted along XY until the lamp is not lit. This position is a distance $x$ from X. The potential difference across $R_1$ is $V_1$ and the potential difference across $R_2$ is $V_2$. What is the value of the ratio $\dfrac{V_1}{V_2}$?

  • A$\dfrac{L}{x}$
  • B$\dfrac{x}{L}$
  • C$\dfrac{L - x}{x}$
  • D$\dfrac{x}{L - x}$

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