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

Kirchhoff's laws — practice question

The diagram illustrates a resistor network. The potential difference across the network is $V$. Is the equation shown below valid for the network? $V = I\left(\frac{1}{R_1} + \frac{1}{R_2} + R_3\right)$

  • AYes, it correctly combines two series resistors with one parallel resistor, and correctly uses Ohm’s Law.
  • BYes, it correctly combines two parallel resistors with one series resistor, and correctly uses Ohm’s Law.
  • CNo, because it should read $V = I \div \left(\frac{1}{R_1} + \frac{1}{R_2} + R_3\right)$.
  • DNo, because the terms $\frac{1}{R_2}$ and $R_3$ have different units and cannot be added.

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