IB Physics SL B 5 13 Series and Parallel Circuits Questions

Practise IB Physics SL B.5.13 by reducing series and parallel networks, assigning current and potential difference correctly, and predicting branch changes.

Exam points

Reduce series and parallel resistor networks using resistance sums and reciprocal rules before calculating total or branch current.
Use same-current series and same-voltage parallel relationships to determine component readings and predict the effect of adding, removing or breaking a branch.
Interpret practical circuit arrangements with ideal meters, lamps, variable resistors and potential dividers to determine voltage, current or resistance.

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Study B.5.13—Series and parallel circuits conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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This question is in two parts. Part 1 is about a thermistor circuit. Part 2 is about vibrations and waves.
Part 1 Thermistor circuit
The circuit shows a negative temperature coefficient (NTC) thermistor X and a $100 \mathrm{k} \Omega$ fixed resistor R connected across a battery.

Figure for Question IB Physics SL B 5 13 Series and Parallel Circuits Questions question 1 — IB Physics SL

The battery has an electromotive force (emf) of 12.0 V and negligible internal resistance.

The graph below shows the variation with temperature T of the resistance $R_{\mathrm{x}}$ of the thermistor.

Determine the temperature of X when the potential difference across R is 4.5 V .

$V_X=7.5\,\mathrm{V}$ $I=\frac{4.5\,\mathrm{V}}{100\times10^3\,\Omega}=4.5\times10^{-5}\,\mathrm{A}$ $R_X=\frac{7.5\,\mathrm{V}}{4.5\times10^{-5}\,\mathrm{A}}=1.67\times10^5\,\Omega$ $T=-37\text{ to }-38\,^{\circ}\mathrm{C}$

Alternatively, use the potential-divider relation V_X/V_R=R_X/R_R or the equivalent resistance calculation.

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IB Physics SL B 5 13 Series and Parallel Circuits Questions question 1