Please write clearly in block capitals.
Centre number Candidate number
A-level
Surname
Forename(s)
PHYSICS
Candidate signature
I declare this is my own work.
7408/3BA
Paper 3 Section B Astrophysics
A-level Mark scheme
PHYSICS June 2026
Paper 3 Version: 1.0 Final
Section B Astrophysics
Monday 8 June 2026 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.
• Fill in the boxes at the top of this page. Question Mark
• 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
• If you need extra space for your answer(s), use the lined pages at the end of
this book. Write the question number against your answer(s). 4
• Do all rough work in this book. Cross through any work you do not want 5
to be marked.
• Show all your working. TOTAL
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.
*jun2674083BA01*
IB/M/Jun26/G4007/V9 7408/3BA
, 2
MARK SCHEME – A-LEVEL PHYSICS – 7408/3BA – JUNE 2026
Do not write
outside the
Section B box
Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant
Answer all questions in this section.
questions, by a panel of subject teachers. This mark scheme includes any amendments made at the
standardisation events which all associates participate in and is the scheme which was used by them in
this examination. The standardisation process ensures that the mark scheme covers the students’
0 1 A reflecting telescope is used to view a star.
responses to questions and that every associate understands and applies it in the same correct way.
The objective mirror of the telescope causes significant spherical aberration.
As preparation for standardisation each associate analyses a number of students’ scripts. Alternative
answers not already covered by the mark scheme are discussed and legislated for. If, after the
0 1 . 1 Complete the paths of the rays on Figure 1 to show how spherical aberration occurs standardisation process, associates encounter unusual answers which have not been raised they are
when using a concave mirror. required to refer these to the Lead Examiner.
[2 marks]
It must be stressed that a mark scheme is a working document, in many cases further developed and
Figure 1 expanded on the basis of students’ reactions to a particular paper. Assumptions about future mark
schemes on the basis of one year’s document should be avoided; whilst the guiding principles of
assessment remain constant, details will change, depending on the content of a particular examination
paper.
No student should be disadvantaged on the basis of their gender identity and/or how they refer to the
gender identity of others in their exam responses.
A consistent use of ‘they/them’ as a singular and pronouns beyond ‘she/her’ or ‘he/him’ will be credited in
exam responses in line with existing mark scheme criteria.
Further copies of this mark scheme are available from
0 1 . 2 Explain the effect of spherical aberration on the image of the star.
[1 mark]
3
information
retains the on all its publications. However, registered schools/colleges for are permitted to copy material from this booklet for their own
internal use, with the following important exception: cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third
party even for internal use within the centre.
and its licensors. All rights reserved.
*02*
2
IB/M/Jun26/7408/3BA
, 3
MARK SCHEME – A-LEVEL PHYSICS – 7408/3BA – JUNE 2026
Do not write
outside the
0 2 . 1 Draw, on Figure 2, the ray diagram for a Cassegrain telescope. box
Your diagram should show the paths of two rays up to the eyepiece. Both rays should Physics - Mark scheme instructions to examiners
initially be parallel to the principal axis.
[3 marks]
1. General
Figure 2
The mark scheme for each question shows:
• the marks available for each part of the question
• the total marks available for the question
• the typical answer or answers which are expected
• extra information to help the Examiner make his or her judgement and help to delineate what is
acceptable or not worthy of credit or, in discursive answers, to give an overview of the area in which a
mark or marks may be awarded.
The extra information is aligned to the appropriate answer in the left-hand part of the mark scheme and
should only be applied to that item in the mark scheme.
At the beginning of a part of a question a reminder may be given, for example: where consequential
marking needs to be considered in a calculation; or the answer may be on the diagram or at a different
place on the script.
In general the right-hand side of the mark scheme is there to provide those extra details which confuse
the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and
consistent.
2. Emboldening
2.1
In a list of acceptable answers where more than one mark is available ‘any two from’ is used, with the
number of marks emboldened. Each of the following bullet points is a potential mark.
2.2
A bold and is used to indicate that both parts of the answer are required to award the mark.
2.3
Alternative answers acceptable for a mark are indicated by the use of or. Different terms in the mark
scheme are shown by a / ; eg allow smooth / free movement.
3. Marking points
3.1 Marking of lists
This applies to questions requiring a set number of responses, but for which candidates have provided
extra responses. The general principle to be followed in such a situation is that ‘right + wrong = wrong’.
Each error/contradiction negates each correct response. So, if the number of errors/contradictions
equals or exceeds the number of marks available for the question, no marks can be awarded.
However, responses considered to be neutral (often prefaced by ‘Ignore’ in the mark scheme) are not
penalised.
Question 2 continues on the next page
Turn over ►
*03*
3
IB/M/Jun26/7408/3BA
Centre number Candidate number
A-level
Surname
Forename(s)
PHYSICS
Candidate signature
I declare this is my own work.
7408/3BA
Paper 3 Section B Astrophysics
A-level Mark scheme
PHYSICS June 2026
Paper 3 Version: 1.0 Final
Section B Astrophysics
Monday 8 June 2026 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.
• Fill in the boxes at the top of this page. Question Mark
• 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
• If you need extra space for your answer(s), use the lined pages at the end of
this book. Write the question number against your answer(s). 4
• Do all rough work in this book. Cross through any work you do not want 5
to be marked.
• Show all your working. TOTAL
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.
*jun2674083BA01*
IB/M/Jun26/G4007/V9 7408/3BA
, 2
MARK SCHEME – A-LEVEL PHYSICS – 7408/3BA – JUNE 2026
Do not write
outside the
Section B box
Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant
Answer all questions in this section.
questions, by a panel of subject teachers. This mark scheme includes any amendments made at the
standardisation events which all associates participate in and is the scheme which was used by them in
this examination. The standardisation process ensures that the mark scheme covers the students’
0 1 A reflecting telescope is used to view a star.
responses to questions and that every associate understands and applies it in the same correct way.
The objective mirror of the telescope causes significant spherical aberration.
As preparation for standardisation each associate analyses a number of students’ scripts. Alternative
answers not already covered by the mark scheme are discussed and legislated for. If, after the
0 1 . 1 Complete the paths of the rays on Figure 1 to show how spherical aberration occurs standardisation process, associates encounter unusual answers which have not been raised they are
when using a concave mirror. required to refer these to the Lead Examiner.
[2 marks]
It must be stressed that a mark scheme is a working document, in many cases further developed and
Figure 1 expanded on the basis of students’ reactions to a particular paper. Assumptions about future mark
schemes on the basis of one year’s document should be avoided; whilst the guiding principles of
assessment remain constant, details will change, depending on the content of a particular examination
paper.
No student should be disadvantaged on the basis of their gender identity and/or how they refer to the
gender identity of others in their exam responses.
A consistent use of ‘they/them’ as a singular and pronouns beyond ‘she/her’ or ‘he/him’ will be credited in
exam responses in line with existing mark scheme criteria.
Further copies of this mark scheme are available from
0 1 . 2 Explain the effect of spherical aberration on the image of the star.
[1 mark]
3
information
retains the on all its publications. However, registered schools/colleges for are permitted to copy material from this booklet for their own
internal use, with the following important exception: cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third
party even for internal use within the centre.
and its licensors. All rights reserved.
*02*
2
IB/M/Jun26/7408/3BA
, 3
MARK SCHEME – A-LEVEL PHYSICS – 7408/3BA – JUNE 2026
Do not write
outside the
0 2 . 1 Draw, on Figure 2, the ray diagram for a Cassegrain telescope. box
Your diagram should show the paths of two rays up to the eyepiece. Both rays should Physics - Mark scheme instructions to examiners
initially be parallel to the principal axis.
[3 marks]
1. General
Figure 2
The mark scheme for each question shows:
• the marks available for each part of the question
• the total marks available for the question
• the typical answer or answers which are expected
• extra information to help the Examiner make his or her judgement and help to delineate what is
acceptable or not worthy of credit or, in discursive answers, to give an overview of the area in which a
mark or marks may be awarded.
The extra information is aligned to the appropriate answer in the left-hand part of the mark scheme and
should only be applied to that item in the mark scheme.
At the beginning of a part of a question a reminder may be given, for example: where consequential
marking needs to be considered in a calculation; or the answer may be on the diagram or at a different
place on the script.
In general the right-hand side of the mark scheme is there to provide those extra details which confuse
the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and
consistent.
2. Emboldening
2.1
In a list of acceptable answers where more than one mark is available ‘any two from’ is used, with the
number of marks emboldened. Each of the following bullet points is a potential mark.
2.2
A bold and is used to indicate that both parts of the answer are required to award the mark.
2.3
Alternative answers acceptable for a mark are indicated by the use of or. Different terms in the mark
scheme are shown by a / ; eg allow smooth / free movement.
3. Marking points
3.1 Marking of lists
This applies to questions requiring a set number of responses, but for which candidates have provided
extra responses. The general principle to be followed in such a situation is that ‘right + wrong = wrong’.
Each error/contradiction negates each correct response. So, if the number of errors/contradictions
equals or exceeds the number of marks available for the question, no marks can be awarded.
However, responses considered to be neutral (often prefaced by ‘Ignore’ in the mark scheme) are not
penalised.
Question 2 continues on the next page
Turn over ►
*03*
3
IB/M/Jun26/7408/3BA
