IB Physics HL Theme B: The particulate nature of matter questions

Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.

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Multiple choice Written

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Question 1

Paper 2Easy7 marks

A student models the apparent brightness $b$ of a star at different distances $d$ assuming the star’s luminosity $L$ remains constant. The relationship is

b=\frac{L}{4\pi d^2}

where $b$ is measured in $\mathrm{W\,m^{-2}}$ $L$ in $\mathrm{W}$ and $d$ in $\mathrm{m}$

Figure 1 shows the modelled apparent brightness as the distance from the star is changed.

(a)

Use Figure 1 to determine the apparent brightness of the star when $d=1.0\times10^{16}\,\mathrm{m}$

[1]

(b)

Using your answer to (a), calculate the luminosity of the star.

[3]

(c)

Use Figure 1 to determine the apparent brightness when $d=2.0\times10^{16}\,\mathrm{m}$

[1]

(d)

State the factor by which the apparent brightness changes when the distance increases from $1.0\times10^{16}\,\mathrm{m}$ to $2.0\times10^{16}\,\mathrm{m}$ and explain this change using the relationship given.

[2]

Question 2

Multiple choiceEasy1 mark

A fixed amount of ideal gas changes between the two states shown. The labelled pressures are absolute; $p$ is a positive pressure and $V$ is a positive volume. Which expression gives $T_B/T_A$

Show answer and explanation

Answer: A. For a fixed amount of ideal gas, $PV/T=\text{constant}$ so $T_B/T_A=P_BV_B/(P_AV_A)$ Substituting the values shown gives $(3p)(2V)/[(2p)(V)]=3$ the temperature ratio is dimensionless.
B: reverses the state ratio, giving $T_A/T_B=1/3$
C: omits the volume ratio and uses pressure alone, giving $3/2$
D: omits the pressure ratio and uses volume alone, giving $2$
Remember: compare the products $PV$ when finding temperature ratios for a fixed amount of ideal gas.

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