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.
7408/1
Paper 1
A-level Mark scheme
PHYSICS June 2026
Paper 1 Version: 1.0 Final
Wednesday 20 May 2026 Afternoon Time allowed: 2 hours
Materials For Examiner’s Use
For this paper you must have:
Question Mark
• a pencil and a ruler
• a scientific calculator 1
• a Data and Formulae Booklet 2
• a protractor.
3
Instructions 4
• Use black ink or black ball-point pen. 5
• Fill in the boxes at the top of this page.
6
• Answer all questions.
• You must answer the questions in the spaces provided. Do not write 7–31
outside the box around each page or on blank pages. TOTAL
• 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).
• Do all rough work in this book. Cross through any work you do not want
to be marked.
• Show all your working.
Information
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 85.
• You are expected to use a scientific calculator where appropriate.
• A Data and Formulae Booklet is provided as a loose insert.
*jun *
IB/M/Jun26/G4007/V9 7408/1
, 2
MARK SCHEME – A-LEVEL PHYSICS – 7408/1 – JUNE 2026
Do not write
outside the
Section A 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 . 1 Describe the simple model of the nitrogen-17 17
7 N atom. responses to questions and that every associate understands and applies it in the same correct way.
As preparation for standardisation each associate analyses a number of students’ scripts. Alternative
[2 marks]
answers not already covered by the mark scheme are discussed and legislated for. If, after the
standardisation process, associates encounter unusual answers which have not been raised they are
required to refer these to the Lead Examiner.
It must be stressed that a mark scheme is a working document, in many cases further developed and
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 nitrogen-17 nucleus is unstable and decays in two steps:
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.
step 1
The nitrogen-17 nucleus decays to form an oxygen-17 17 ( )
8 O nucleus in an
Further copies of this mark scheme are available from
excited state.
step 2
The excited oxygen-17 nucleus becomes a stable isotope by emitting a neutron.
0 1 . 2 State the fundamental force involved in step 1.
Go on to explain your answer.
[2 marks]
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/Jun26/7408/1
, 3
MARK SCHEME – A-LEVEL PHYSICS – 7408/1 – JUNE 2026
Do not write
outside the
0 1 . 3 Describe, for step 2, the properties of the force that keeps the de-excited oxygen-17 box
nucleus stable.
[2 marks] Physics - Mark scheme instructions to examiners
1. General
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
The neutron emitted in step 2 decays into a baryon and other particles. 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.
0 1 . 4 State the names of the leptons that are produced in neutron decay.
[1 mark] 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
0 1 . 5 State the name of the baryon that is produced in neutron decay.
the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and
Go on to comment on the stability of this baryon.
consistent.
[1 mark]
2. Emboldening
8 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.
Turn over for the next question
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.
Turn over ►
*03*
3
IB/M/Jun26/7408/1
, 4
MARK SCHEME – A-LEVEL PHYSICS – 7408/1 – JUNE 2026
Do not write
outside the
0 2 This question is about the photoelectric effect. box
3.2 Marking procedure for calculations
Figure 1 shows an electroscope.
Full marks can usually be given for a correct numerical answer without working shown unless the
In this electroscope, the top of a gold leaf is attached to a metal rod. The metal rod is
question states ‘Show your working’. However, if a correct numerical answer can be evaluated from
attached to a metal cap.
incorrect physics then working will be required. The mark scheme will indicate both this and the credit (if
When the cap is given a charge, the bottom of the leaf is repelled from the rod through
any) that can be allowed for the incorrect approach.
an angle θ as shown in Figure 1. However, if the answer is incorrect, mark(s) can usually be gained by correct substitution/working and
this is shown in the ‘extra information’ column or by each stage of a longer calculation.
The greater the charge on the electroscope, the greater the angle θ.
A calculation must be followed through to answer in decimal form. An answer in surd form is never
Figure 1 acceptable for the final (evaluation) mark in a calculation and will therefore generally be denied one
mark.
3.3 Interpretation of ‘it’
Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the correct
subject.
3.4 Errors carried forward, consequential marking and arithmetic errors
Allowances for errors carried forward are likely to be restricted to calculation questions and should be
shown by the abbreviation ECF or conseq in the marking scheme.
An arithmetic error should be penalised for one mark only unless otherwise amplified in the marking
scheme. Arithmetic errors may arise from a slip in a calculation or from an incorrect transfer of a
numerical value from data given in a question.
3.5 Phonetic spelling
The phonetic spelling of correct scientific terminology should be credited (eg fizix) unless there is a
possible confusion (eg defraction/refraction) with another technical term.
3.6 Brackets
(…..) are used to indicate information which is not essential for the mark to be awarded but is included to
help the examiner identify the sense of the answer required.
In a demonstration, the cap is given a negative charge.
Monochromatic light is then incident on the cap. 3.7 Ignore / Insufficient / Do not allow
When the light has a frequency less than a particular threshold frequency f0, ‘Ignore’ or ‘insufficient’ is used when the information given is irrelevant to the question or not enough to
the angle θ does not change. gain the marking point. Any further correct amplification could gain the marking point.
When the light has a frequency greater than f0, the gold leaf immediately falls back to
‘Do not allow’ means that this is a wrong answer which, even if the correct answer is given, will still
the rod so that θ is zero. mean that the mark is not awarded.
The cap is made from a metal M. The work function of M is 5.01 eV. 3.8 Significant figure penalties
Answers to questions in the practical sections (7407/2 – Section A and 7408/3A) should display an
0 2 . 1 Explain what is meant by a work function of 5.01 eV. appropriate number of significant figures. For non-practical sections, an A-level paper may contain up to
[1 mark] 2 marks (1 mark for AS) that are contingent on the candidate quoting the final answer in a calculation to
a specified number of significant figures (sf). This will generally be assessed to be the number of sf of
the datum with the least number of sf from which the answer is determined. The mark scheme will give
the range of sf that are acceptable but this will normally be the sf of the datum (or this sf −1).
An answer in surd form cannot gain the sf mark. An incorrect calculation following some working can
gain the sf mark. For a question beginning with the command word ‘Show that…’, the answer should be
quoted to one more sf than the sf quoted in the question eg ‘Show that X is equal to about 2.1 cm’ –
answer should be quoted to 3 sf. An answer to 1 sf will not normally be acceptable, unless the answer is
an integer eg a number of objects. In non-practical sections, the need for a consideration will be
indicated in the question by the use of ‘Give your answer to an appropriate number of significant figures’.
*04*
4
IB/M/Jun26/7408/1
Centre number Candidate number
A-level
Surname
Forename(s)
PHYSICS
Candidate signature
I declare this is my own work.
7408/1
Paper 1
A-level Mark scheme
PHYSICS June 2026
Paper 1 Version: 1.0 Final
Wednesday 20 May 2026 Afternoon Time allowed: 2 hours
Materials For Examiner’s Use
For this paper you must have:
Question Mark
• a pencil and a ruler
• a scientific calculator 1
• a Data and Formulae Booklet 2
• a protractor.
3
Instructions 4
• Use black ink or black ball-point pen. 5
• Fill in the boxes at the top of this page.
6
• Answer all questions.
• You must answer the questions in the spaces provided. Do not write 7–31
outside the box around each page or on blank pages. TOTAL
• 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).
• Do all rough work in this book. Cross through any work you do not want
to be marked.
• Show all your working.
Information
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 85.
• You are expected to use a scientific calculator where appropriate.
• A Data and Formulae Booklet is provided as a loose insert.
*jun *
IB/M/Jun26/G4007/V9 7408/1
, 2
MARK SCHEME – A-LEVEL PHYSICS – 7408/1 – JUNE 2026
Do not write
outside the
Section A 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 . 1 Describe the simple model of the nitrogen-17 17
7 N atom. responses to questions and that every associate understands and applies it in the same correct way.
As preparation for standardisation each associate analyses a number of students’ scripts. Alternative
[2 marks]
answers not already covered by the mark scheme are discussed and legislated for. If, after the
standardisation process, associates encounter unusual answers which have not been raised they are
required to refer these to the Lead Examiner.
It must be stressed that a mark scheme is a working document, in many cases further developed and
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 nitrogen-17 nucleus is unstable and decays in two steps:
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.
step 1
The nitrogen-17 nucleus decays to form an oxygen-17 17 ( )
8 O nucleus in an
Further copies of this mark scheme are available from
excited state.
step 2
The excited oxygen-17 nucleus becomes a stable isotope by emitting a neutron.
0 1 . 2 State the fundamental force involved in step 1.
Go on to explain your answer.
[2 marks]
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/Jun26/7408/1
, 3
MARK SCHEME – A-LEVEL PHYSICS – 7408/1 – JUNE 2026
Do not write
outside the
0 1 . 3 Describe, for step 2, the properties of the force that keeps the de-excited oxygen-17 box
nucleus stable.
[2 marks] Physics - Mark scheme instructions to examiners
1. General
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
The neutron emitted in step 2 decays into a baryon and other particles. 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.
0 1 . 4 State the names of the leptons that are produced in neutron decay.
[1 mark] 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
0 1 . 5 State the name of the baryon that is produced in neutron decay.
the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and
Go on to comment on the stability of this baryon.
consistent.
[1 mark]
2. Emboldening
8 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.
Turn over for the next question
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.
Turn over ►
*03*
3
IB/M/Jun26/7408/1
, 4
MARK SCHEME – A-LEVEL PHYSICS – 7408/1 – JUNE 2026
Do not write
outside the
0 2 This question is about the photoelectric effect. box
3.2 Marking procedure for calculations
Figure 1 shows an electroscope.
Full marks can usually be given for a correct numerical answer without working shown unless the
In this electroscope, the top of a gold leaf is attached to a metal rod. The metal rod is
question states ‘Show your working’. However, if a correct numerical answer can be evaluated from
attached to a metal cap.
incorrect physics then working will be required. The mark scheme will indicate both this and the credit (if
When the cap is given a charge, the bottom of the leaf is repelled from the rod through
any) that can be allowed for the incorrect approach.
an angle θ as shown in Figure 1. However, if the answer is incorrect, mark(s) can usually be gained by correct substitution/working and
this is shown in the ‘extra information’ column or by each stage of a longer calculation.
The greater the charge on the electroscope, the greater the angle θ.
A calculation must be followed through to answer in decimal form. An answer in surd form is never
Figure 1 acceptable for the final (evaluation) mark in a calculation and will therefore generally be denied one
mark.
3.3 Interpretation of ‘it’
Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the correct
subject.
3.4 Errors carried forward, consequential marking and arithmetic errors
Allowances for errors carried forward are likely to be restricted to calculation questions and should be
shown by the abbreviation ECF or conseq in the marking scheme.
An arithmetic error should be penalised for one mark only unless otherwise amplified in the marking
scheme. Arithmetic errors may arise from a slip in a calculation or from an incorrect transfer of a
numerical value from data given in a question.
3.5 Phonetic spelling
The phonetic spelling of correct scientific terminology should be credited (eg fizix) unless there is a
possible confusion (eg defraction/refraction) with another technical term.
3.6 Brackets
(…..) are used to indicate information which is not essential for the mark to be awarded but is included to
help the examiner identify the sense of the answer required.
In a demonstration, the cap is given a negative charge.
Monochromatic light is then incident on the cap. 3.7 Ignore / Insufficient / Do not allow
When the light has a frequency less than a particular threshold frequency f0, ‘Ignore’ or ‘insufficient’ is used when the information given is irrelevant to the question or not enough to
the angle θ does not change. gain the marking point. Any further correct amplification could gain the marking point.
When the light has a frequency greater than f0, the gold leaf immediately falls back to
‘Do not allow’ means that this is a wrong answer which, even if the correct answer is given, will still
the rod so that θ is zero. mean that the mark is not awarded.
The cap is made from a metal M. The work function of M is 5.01 eV. 3.8 Significant figure penalties
Answers to questions in the practical sections (7407/2 – Section A and 7408/3A) should display an
0 2 . 1 Explain what is meant by a work function of 5.01 eV. appropriate number of significant figures. For non-practical sections, an A-level paper may contain up to
[1 mark] 2 marks (1 mark for AS) that are contingent on the candidate quoting the final answer in a calculation to
a specified number of significant figures (sf). This will generally be assessed to be the number of sf of
the datum with the least number of sf from which the answer is determined. The mark scheme will give
the range of sf that are acceptable but this will normally be the sf of the datum (or this sf −1).
An answer in surd form cannot gain the sf mark. An incorrect calculation following some working can
gain the sf mark. For a question beginning with the command word ‘Show that…’, the answer should be
quoted to one more sf than the sf quoted in the question eg ‘Show that X is equal to about 2.1 cm’ –
answer should be quoted to 3 sf. An answer to 1 sf will not normally be acceptable, unless the answer is
an integer eg a number of objects. In non-practical sections, the need for a consideration will be
indicated in the question by the use of ‘Give your answer to an appropriate number of significant figures’.
*04*
4
IB/M/Jun26/7408/1
