2025 AQA A-Level PHYSICS 7408/3BD
Section B Turning points in physics
Question paper and Marking scheme Merged
Please write clearly in block capitals.
Centre number Candidate number
Surname
Forename(s)
Candidate signature
I declare this is my own work.
A-level
PHYSICS
Paper 3
Section B Turning points in physics
Tuesday 17 June 2025 Morning Time allowed: The total time for
both sections of this paper is
Materials
2 hours. You are advised to
For this paper you must have:
• a pencil and a ruler spend approximately
• a scientific calculator 50 minutes on this section.
• a Data and Formulae Booklet
• a protractor.
Instructions For Examiner’s Use
• Use black ink or black ball-point pen.
Question Mark
• Fill in the boxes at the top of this page.
• Answer all questions. 1
• You must answer the questions in the spaces provided. Do not write 2
outside the box around each page or on blank pages. 3 IB/M/Jun25/G40
• If you need extra space for your answer(s), use the lined pages at the end of
4
this book. Write the question number against your answer(s).
• Do all rough work in this book. Cross through any work you do not want TOTAL
to be marked.
• Show all your working.
Information
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 35.
• You are expected to use a scientific calculator where appropriate.
• A Data and Formulae Booklet is provided as a loose insert.
, 2
Do not write
outside the
Section B box
Answer all questions in this section.
0 1 This question is about Thomson’s determination of the electron’s specific charge.
You should not use the values of the electron charge, mass or specific charge from
the data and formulae booklet in this question.
Figure 1 shows part of the apparatus that Thomson used to measure the specific
charge of the electron.
Figure 1
0 1 . 1 A modern version of Thomson’s apparatus uses thermionic emission in the production
of the electron beam.
Suggest how the electron beam is produced in this modern version.
You should include a labelled diagram and suitable values for the power supplies
used.
[3 marks]
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IB/M/Jun25/7408/3BD
, 3
Do not write
outside the
box
Question 1 continues on the next page
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, 4
Do not write
outside the
A potential difference (pd) of 750 V is applied between the horizontal parallel plates. box
Figure 2 shows the plates and the path of the electrons.
Figure 2
The electrons enter the electric field between the plates at S and leave it at T with
speed v. Beyond T the electrons travel in a straight line at an angle θ.
θ is read from a scale on a fluorescent screen.
The plates are of length 10.0 cm and are separated by a distance of 5.00 cm.
0 1 . 2 A uniform magnetic field of flux density 0.640 mT is now applied between the plates.
This returns the electron beam to its undeflected position.
Show that the horizontal component of the velocity of the electrons is approximately
2.3 × 107 m s−1.
[2 marks]
The magnetic field is switched off and θ is measured to be 25°.
0 1 . 3 Show that the vertical component of the velocity of the electrons at T is approximately
1.1 × 107 m s−1.
[1 mark]
for more: tyrionpapers.com
IB/M/Jun25/7408/3BD
Section B Turning points in physics
Question paper and Marking scheme Merged
Please write clearly in block capitals.
Centre number Candidate number
Surname
Forename(s)
Candidate signature
I declare this is my own work.
A-level
PHYSICS
Paper 3
Section B Turning points in physics
Tuesday 17 June 2025 Morning Time allowed: The total time for
both sections of this paper is
Materials
2 hours. You are advised to
For this paper you must have:
• a pencil and a ruler spend approximately
• a scientific calculator 50 minutes on this section.
• a Data and Formulae Booklet
• a protractor.
Instructions For Examiner’s Use
• Use black ink or black ball-point pen.
Question Mark
• Fill in the boxes at the top of this page.
• Answer all questions. 1
• You must answer the questions in the spaces provided. Do not write 2
outside the box around each page or on blank pages. 3 IB/M/Jun25/G40
• If you need extra space for your answer(s), use the lined pages at the end of
4
this book. Write the question number against your answer(s).
• Do all rough work in this book. Cross through any work you do not want TOTAL
to be marked.
• Show all your working.
Information
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 35.
• You are expected to use a scientific calculator where appropriate.
• A Data and Formulae Booklet is provided as a loose insert.
, 2
Do not write
outside the
Section B box
Answer all questions in this section.
0 1 This question is about Thomson’s determination of the electron’s specific charge.
You should not use the values of the electron charge, mass or specific charge from
the data and formulae booklet in this question.
Figure 1 shows part of the apparatus that Thomson used to measure the specific
charge of the electron.
Figure 1
0 1 . 1 A modern version of Thomson’s apparatus uses thermionic emission in the production
of the electron beam.
Suggest how the electron beam is produced in this modern version.
You should include a labelled diagram and suitable values for the power supplies
used.
[3 marks]
for more: tyrionpapers.com
IB/M/Jun25/7408/3BD
, 3
Do not write
outside the
box
Question 1 continues on the next page
Turn over ►
for more: tyrionpapers.com
IB/M/Jun25/7408/3BD
, 4
Do not write
outside the
A potential difference (pd) of 750 V is applied between the horizontal parallel plates. box
Figure 2 shows the plates and the path of the electrons.
Figure 2
The electrons enter the electric field between the plates at S and leave it at T with
speed v. Beyond T the electrons travel in a straight line at an angle θ.
θ is read from a scale on a fluorescent screen.
The plates are of length 10.0 cm and are separated by a distance of 5.00 cm.
0 1 . 2 A uniform magnetic field of flux density 0.640 mT is now applied between the plates.
This returns the electron beam to its undeflected position.
Show that the horizontal component of the velocity of the electrons is approximately
2.3 × 107 m s−1.
[2 marks]
The magnetic field is switched off and θ is measured to be 25°.
0 1 . 3 Show that the vertical component of the velocity of the electrons at T is approximately
1.1 × 107 m s−1.
[1 mark]
for more: tyrionpapers.com
IB/M/Jun25/7408/3BD
