IB Physics Paper 1B · SL data-based questions practice papers
SL · 20 marks · 2 questions on experimental data. Each generated paper follows the SL & HL Paper 1B · SL data-based questions format, with the same number and style of questions as the real exam, and comes with an IB-style mark scheme.
Sample Paper 1B · SL data-based questions questions
Question 1Structured · 11 marksA* challenge
A student uses a simple pendulum to determine the acceleration of free fall g. She measures the length L of the string from the point of suspension to the top of the bob, and times 10 complete oscillations with a stopwatch.
L / m ± 0.002
0.20
0.35
0.50
0.65
0.80
time for 10 oscillations / s ± 0.2
9.2
12.0
14.3
16.4
18.0
T2 / s2
0.85
1.44
2.05
2.69
3.24
Table 1.1
(a)
Explain why the student timed 10 oscillations rather than one.
[1]
(b)
Calculate the percentage uncertainty in T2 for L = 0.20 m.
[2]
Fig. 1.1
(c)
The graph shows T2 against L with error bars for T2. Draw the line of best fit and use it to determine g.
[4]
(d)
The line does not pass through the origin. Explain this, and use the graph to estimate the radius of the bob.
[3]
(e)
State why the systematic error in L does not affect the value of g found from the gradient.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
reduces percentage uncertainty
the absolute uncertainty (reaction time) is the same, so the percentage uncertainty in T is ten times smaller ✓
line of best fit through all error bars ✓ gradient = 4.01 s2 m−1 (accept 3.81 to 4.22) ✓ g = 4π2gradient✓ g = 9.83 m s−2 (accept 9.34 to 10.3) ✓
4
(d)
r ≈ −1.15 cm
L was measured to the top of the bob, so the true length is L + r (a systematic error) ✓ the line meets the L-axis at L ≈ −−0.0115 m ✓ radius ≈ −1.15 cm ✓
3
(e)
gradient unaffected by offset
a constant offset shifts the line but does not change its gradient ✓
1
Question 2Structured · 10 marksA* challenge
A fixed mass of air is trapped in a syringe at a room temperature of 20 °C. The volume V is changed slowly and the pressure p is read from a gauge.
V / cm3 ± 1
20
25
30
40
50
p / kPa ± 5
492
388
322
243
195
Table 2.1
(a)
Explain why the volume should be changed slowly.
[1]
(b)
State what graph the student should plot to obtain a straight line through the origin.
[1]
Fig. 2.1
(c)
Use the graph to determine the number of moles of air in the syringe.
[4]
(d)
Determine the percentage uncertainty in V for the smallest volume, and state whether it or the uncertainty in p is more significant.
[2]
(e)
Air can leak past the plunger at high pressure. State and explain the effect of this on the graph.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
keep temperature constant
so that the temperature of the gas stays constant (isothermal) ✓
120 × 100 = 5.00% ✓ compared with 5492 × 100 = 1.02% for p, so V is more significant ✓
2
(e)
gradient falls
n decreases at high pressure (small V, large 1/V) ✓ so points at high 1/V fall below the line; the graph curves downwards ✓
2
Question 3Structured · 10 marks
A student measures the terminal potential difference V across a cell for different currents I, by changing a variable resistor in series with the cell and an ammeter.
I / A ± 0.01
0.08
0.17
0.25
0.33
0.42
V / V ± 0.02
1.38
1.28
1.21
1.11
1.02
Table 3.1
Fig. 3.1
(a)
Write down the equation relating V, I, the emf ε and the internal resistance r.
[1]
(b)
Use the graph to determine ε and r.
[4]
(c)
Calculate the maximum power that the cell can deliver to an external resistor.
[2]
(d)
The student suggests that a larger range of currents would improve the experiment. Discuss one advantage and one disadvantage.
[2]
(e)
Explain why the switch should be opened between readings.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
V = ε − Ir
V = ε − Ir ✓
1
(b)
ε ≈ 1.47 V, r ≈ 1.08 Ω
line of best fit drawn ✓ ε = y-intercept = 1.47 V ✓ r = −gradient ✓ r = 1.08 Ω (accept ±10%) ✓
4
(c)
0.500 W
maximum when R = r, so P = ε24r✓ 0.500 W ✓
2
(d)
range vs heating
a wider range spreads the points and reduces the uncertainty in the gradient ✓ larger currents heat the cell, changing r, or drain it so ε falls ✓
2
(e)
avoid heating / discharge
so the cell does not heat up or run down, keeping ε and r constant ✓
1
Question 4Structured · 9 marks
A student shines a ray of light into a semicircular glass block and measures the angle of incidence i in air and the angle of refraction r in the glass with a protractor (± 1°).
i / °
20
30
40
50
60
70
r / °
13
18
24
28
34
37
Table 4.1
(a)
Calculate the percentage uncertainty in r for i = 20°, and explain why small angles give less reliable results.
[2]
Fig. 4.1
(b)
The graph shows sin i against sin r. Use it to determine the refractive index of the glass.
[2]
(c)
Calculate the critical angle for the glass.
[2]
(d)
Calculate the speed of light in the glass.
[2]
(e)
Explain why a semicircular block is used, with the ray aimed at the centre of its flat face.
[1]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
7.69%
113 × 100 = 7.69% ✓ the same ±1° is a larger fraction of a small angle ✓
2
(b)
1.56
refractive index = gradient ✓ n = 1.56 (accept 1.50 to 1.62) ✓
2
(c)
39.8°
sin c = 1n✓ c = 39.8° ✓
2
(d)
1.92 × 108 m s−1
v = cn✓ 1.92 × 108 m s−1✓
2
(e)
no refraction at curved face
the ray leaves along a radius, so it is not refracted at the curved surface ✓
1
Question 5Structured · 10 marks
A student investigates how the resistance R of a wire varies with its length L. The diameter of the wire is measured with a micrometer as 0.38 ± 0.01 mm. R is measured with a digital ohmmeter.
L / m ± 0.001
0.20
0.40
0.60
0.80
1.00
R / Ω ± 0.1
1.2
2.0
2.9
3.8
4.7
Table 5.1
(a)
Calculate the percentage uncertainty in the cross-sectional area of the wire.
[2]
Fig. 5.1
(b)
Use the graph to determine the resistivity of the metal.
[3]
(c)
The line has a positive intercept on the R-axis. Suggest a reason for this.
[2]
(d)
The uncertainty in the gradient is estimated to be 4%. Determine the absolute uncertainty in the resistivity.
[2]
(e)
Suggest one way the student could reduce the percentage uncertainty in the cross-sectional area.
gradient = 4.39 Ω m−1✓ A = π(d2)2 = 1.13 × 10−7 m2✓ ρ = gradient × A = 5.0 × 10−7 Ω m (accept ±5%) ✓
3
(c)
contact resistance
a resistance that is present even when L = 0 ✓ e.g. resistance of the leads/contacts or a zero error of the ohmmeter (systematic error) ✓
2
(d)
± 5 × 10−8 Ω m
%Δρ = 4% + 5.26% = 9.26% ✓ Δρ = 5 × 10−8 Ω m ✓
2
(e)
repeat diameter readings
measure the diameter at several points and orientations and average, or use a thicker wire ✓
1
Question 6Structured · 11 marks
A student heats a 0.5 kg block of aluminium with an electrical heater. The potential difference across the heater is 12.0 ± 0.1 V and the current is 4.6 ± 0.1 A. A thermometer in the block is read every 60 s.
t / s
60
120
180
240
300
360
θ / °C ± 0.5
23.9
30.6
37.6
44.1
50.9
57.8
Table 6.1
(a)
Calculate the power of the heater and its percentage uncertainty.
[3]
(b)
Use the data to determine the specific heat capacity of the block.
[3]
(c)
The accepted value for aluminium is 900 J kg−1 K−1. Explain why the experimental value is larger.
[2]
(d)
Suggest why the temperature does not rise during the first part of the heating.
[1]
(e)
Suggest two improvements to the experiment.
[2]
Show answers and mark scheme
Part
Answer and marking points
Marks
(a)
55.2 W ± 3.01%
P = VI = 55.2 W ✓ percentage uncertainties add ✓ 0.112.0 + 0.14.6 → 3.01% ✓
3
(b)
976 J kg−1 K−1
rate of temperature rise = 0.113 K s−1 from the linear region ✓ c = Pm × (Δθ/Δt)✓ c ≈ 976 J kg−1 K−1 (accept ±8%) ✓
3
(c)
thermal energy lost
some energy is transferred to the surroundings / not all goes into the block ✓ so the temperature rise is smaller than expected, giving a larger calculated c ✓
2
(d)
heater warms up first
the heater and thermometer take time to warm up / thermal energy takes time to conduct to the thermometer ✓
1
(e)
insulate; oil in holes
insulate the block (lagging) ✓ put oil/thermal paste in the holes for good thermal contact (or start below room temperature and finish the same amount above) ✓
Riyaz Shaikh has mentored IGCSE, IB and A Level students for 15+ years, one-on-one, online and in Mumbai. The hardest questions on this site are the ones he uses to find a student's weak points.
Original IB-style practice questions written for mentorriyaz.in. These are not IB past paper questions, and this site is not affiliated with or endorsed by the International Baccalaureate Organization. Updated 2026-11-04. Paper generator · mentorriyaz.in