IB Physics SL 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 2Medium11 marks

An observer on Earth measures the apparent brightness of stars A and B shown in Figure 1. Assume that both stars emit uniformly in all directions and that absorption between each star and Earth is negligible.

(a)

State which star has the greater apparent brightness.

[1]

(b)

Determine the ratio $L_B/L_A$

[3]

(c)

Calculate the luminosity of star A.

[2]

(d)

A third star, C, has twice the luminosity of star A and an apparent brightness of $1.2\times10^{-8}\,\mathrm{W\,m^{-2}}$ Determine its distance from Earth.

[3]

(e)

Explain why the apparent brightness of a star decreases as its distance from Earth increases, if its luminosity is unchanged.

[2]

Question 2

Paper 2Easy6 marks

Infrared radiation emitted by Earth’s surface reaches a carbon dioxide molecule in the atmosphere. Figure 1 shows two possible incoming infrared photons and two energy levels of the molecule. The molecule’s natural vibration frequency is $f_0$ In this model, a photon of frequency $f$ has energy $E=hf$

(a)

Using Figure 1, identify which photon can be absorbed by the molecule. Explain your choice using the resonance model and the energy levels.

[3]

(b)

As the molecule returns from $E_1$ to $E_0$ state the frequency of the infrared radiation emitted.

[1]

(c)

State the directions in which the radiation is emitted and explain how this can contribute to the greenhouse effect at Earth’s surface.

[2]

Question 3

Paper 2Medium8 marks

An ideal gas is in a vessel of uniform pressure. Figure 1 shows the gas and a surface $S$ of the vessel. The force shown is the resultant force exerted by the gas on $S$

Use $N_A=6.02\times10^{23}\ \mathrm{mol^{-1}}$ and $R=8.31\ \mathrm{J\,mol^{-1}\,K^{-1}}$ Give answers to three significant figures, except in (d), where give the temperature to the nearest degree Celsius.

(a)

Determine the pressure of the gas.

[2]

(b)

Determine the amount of substance of the gas.

[2]

(c)

Using your answers to (a) and (b), determine the temperature of the gas in kelvin.

[3]

(d)

Express the temperature from (c) in degrees Celsius.

[1]

Question 4

Paper 2Hard10 marks

A fixed amount of gas is measured in a cylinder with a movable piston. Figure 1 shows the measured pressure–volume states of the gas at two temperatures. The temperatures are in kelvin. $X$ is a further state of the same gas, at an unrecorded temperature. No curves have been fitted to the measurements.

(a)

Describe the pressure–volume relationship indicated by the $300\ \mathrm{K}$ measurements.

[1]

(b)

For the measurements at $V=2.00\ \mathrm{L}$ calculate $PV/T$ at each temperature. Give an appropriate unit.

[2]

(c)

A fixed amount of gas changes from state 1 $(P_1,V_1,T_1)$ to state 2 $(P_2,V_2,T_2)$ Using the empirical pressure–temperature law at constant volume and Boyle’s law at constant temperature, derive a relation between these two states. Temperatures are in kelvin.

[2]

(d)

A controller is expected to switch when the gas reaches $750\ \mathrm{K}$ Use state $X$ and both calibration results from part (b) to estimate the temperature at $X$ and decide whether the controller’s reported temperature is consistent with the measurements. Show your working.

[5]

Question 5

Paper 2Hard10 marks

Two samples, $X$ and $Y$ have the same length and cross-sectional area. Sample $X$ is a metal; sample $Y$ is an unknown material. Each sample is connected separately to a variable d.c. supply. The potential difference $V$ across the sample and the current $I$ through it are measured at the same temperature.

(a)

Using Figure 1, read the current in each sample when the potential difference is $3.0\ \text{V}$

[2]

(b)

Use the reading for sample $X$ at $3.0\ \text{V}$ to determine its resistance.

[2]

(c)

A third test uses a sample $S$ which is either $X$ or $Y$ It is connected in series with a $50\ \Omega$ resistor to a $6.0\ \text{V}$ supply. The current in the circuit is $60\ \text{mA}$ Use the circuit information and Figure 1 to determine whether $S$ matches $X$ or (Y). Show your reasoning.

[4]

(d)

A student claims that sample $Y$ has no mobile charge carriers because its current is almost zero. Assess this claim using Figure 1 and the idea of mobility of charge carriers.

[2]

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