Physics 9702 · AS & A Level · Kirchhoff's laws

Kirchhoff's laws — practice question

For two resistors with resistances $R_1$ and $R_2$ connected in parallel, the total resistance $R_T$ is given by the formula shown below. $$\frac{1}{R_T} = \frac{1}{R_1} + \frac{1}{R_2}$$ Which statement is used to derive this formula?

  • AThe currents through the two resistors are equal.
  • BThe potential difference across each resistor is the same.
  • CThe supply current is split between the two resistors in the same ratio as the ratio of their resistances.
  • DThe total power dissipated is the sum of the powers dissipated in the two resistors separately.

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