Physics 9702 · AS & A Level · Potential difference and power
Potential difference and power — practice question
As shown in Fig. 5.1, a $240\,\text{V}$ power supply $S$ with negligible internal resistance is connected to four resistors. A pair of resistors of resistance $550\,\Omega$ and $950\,\Omega$ is connected in series across $S$. Another pair, with resistances $350\,\Omega$ and $R$, is also connected in series across $S$. The current delivered by $S$ is $0.40\,\text{A}$. Currents $I_1$ and $I_2$ are shown in Fig. 5.1.
(a(i))[2]
Calculate the current $I_1$.
(a(ii))[2]
Calculate the resistance $R$.
(a(iii))[2]
Calculate the ratio of the power transformed in the $350\,\Omega$ resistor to that transformed in the $550\,\Omega$ resistor.
(b(i))[2]
As shown in Fig. 5.1, two points are marked A and B. Calculate the potential difference $V_{AB}$ between A and B.
(b(ii))[1]
The resistance $R$ is increased. State and explain what happens to $V_{AB}$.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Applying $I = V/R$” …