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.

Type

Multiple choice Written

Difficulty

Easy Medium Hard

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

Paper 2Medium8 marks

Satellite measurements estimate the daily-mean incident and reflected short-wave solar power per unit area for regions with the same underlying surface type. The two regions measured on day 2 were observed in the same season and had approximately matched cloud cover.

Observation	Latitude	Cloud cover	Incident solar power / W m⁻²	Reflected solar power / W m⁻²
Day 1	30°N	Low	250	50
Day 2	30°N	Extensive	250	90
Day 2	60°N	Extensive	180	81

(a)

Determine the albedo for each of the three observations.

[3]

(b)

Calculate the absorbed solar power per unit area at 30°N on day 1 and day 2.

[2]

(c)

Use your answers to (a) and (b) to explain how changing cloud cover affects the daily albedo and absorbed solar power per unit area at 30°N.

[2]

(d)

State what the comparison between the two day-2 observations suggests about the dependence of albedo on latitude.

[1]

Question 3

Paper 2Medium13 marks

A laboratory investigates the pressure exerted by a gas on flat panels. In each trial, a panel forms one wall of a chamber. The outer face of the panel is evacuated, and a sensor measures the force exerted by the gas perpendicular to the panel. The panel area is changed between trials. The measured forces are shown in Figure 1.

(a)

Write the equation defining pressure, P, in terms of force and area, and state what the force represents.

[2]

(b)

Use Figure 1 to determine the pressure represented by the graph, in Pa.

[3]

(c)

A further panel is exposed to gas at the pressure determined in (b). The area of the panel is 0.075 m². Determine the magnitude of the force exerted on the panel.

[2]

(d)

A panel of area 0.12 m² is exposed to gas at the pressure determined in (b). The panel is tilted. Determine the magnitude of the force exerted on it and state the force’s direction relative to the panel.

[3]

(e)

A student concludes that gas pressure increases with panel area because the force shown in Figure 1 increases. Assess this conclusion using the graph.

[3]

Question 4

Paper 2Hard10 marks

A cyclic engine operates between two thermal reservoirs at $480\ \mathrm{K}$ and $300\ \mathrm{K}$ The engine, both reservoirs and an ideal mechanical work store form an isolated assembly. The engine returns to its initial state each cycle, and the work store’s entropy does not change.

For a reservoir at constant temperature, its entropy change is $\Delta S=Q/T$ where $Q$ is the energy received by the reservoir.

(a)

State the Clausius form and the Kelvin form of the second law of thermodynamics.

[2]

(b)

In one proposed cycle, the engine receives $1.20\ \mathrm{kJ}$ from the $480\ \mathrm{K}$ reservoir, transfers $0.50\ \mathrm{kJ}$ to the $300\ \mathrm{K}$ reservoir and delivers $0.70\ \mathrm{kJ}$ to the work store.

Assess whether this proposed cycle is consistent with energy conservation and the second law.

[4]

(c)

The engine continues to receive $1.20\ \mathrm{kJ}$ from the $480\ \mathrm{K}$ reservoir each cycle. Determine the greatest possible work delivered to the work store per cycle, consistent with the second law, and state whether the limiting cycle is reversible or irreversible.

[4]

Question 5

Paper 2Medium7 marks

A positive charge $q$ moves between the terminals of component P or component Q in the direction of conventional current. $W$ is the electrical work transferred to the component. For each component, the potential difference is constant during the measurements. Figure 1 shows measured values of $W$ for different values of $q$ Treat potential differences as magnitudes.

(a)

Explain why the gradient of a graph of $W$ against $q$ represents the potential difference across a component.

[2]

(b)

Determine the potential difference across component P using Figure 1.

[2]

(c)

A positive charge of $0.60\ \mathrm{C}$ passes through component Q. Determine the work transferred to Q. State which component transfers more energy per unit charge, and by what factor.

[3]

Question 6

Paper 2Medium9 marks

The circuits in Figure 1 are used to compare solid samples X and Y. The sources are ideal and the ammeters have negligible resistance. The samples have equal length and cross-sectional area and are each maintained at $20^\circ\mathrm{C}$

(a)

Identify which sample is an insulator.

[1]

(b)

Determine the resistance of each sample.

[3]

(c)

The voltage across X is then reduced to $1.5\ \mathrm{V}$ Its temperature remains at $20^\circ\mathrm{C}$ and its resistance is assumed unchanged. Calculate the electrical energy transferred to X in $40\ \mathrm{s}$ Show your working.

[3]

(d)

Explain, in terms of the mobility of charge carriers, why the readings in Figure 1 are consistent with X being a conductor and Y an insulator.

[2]

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