Physics 9702 · AS & A Level · Practical circuits

Practical circuits — practice question

The potential differences in two resistors with resistances $R_1$ and $R_2$ are being compared by means of a potentiometer wire (a wire of uniform resistance) in the electrical circuit illustrated. One end of a galvanometer is attached to point X. The galvanometer shows zero when its other end is joined to a point located $60\,\text{cm}$ from one end of the potentiometer wire. One end of a second galvanometer is attached to point Y. This galvanometer shows zero when its other end is joined to a point located $80\,\text{cm}$ from the same end of the potentiometer wire. Determine the ratio $\frac{R_2}{R_1}$?

  • A$\frac{1}{3}$
  • B$\frac{3}{4}$
  • C$3$
  • D$\frac{4}{3}$

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