2025 OCR A Level Physics A
H556/03 Unified physics
Verified Question paper with Marking Scheme
Attached
Oxford Cambridge and RSA
Tuesday 17 June 2025 – Morning
A Level Physics A
H556/03 Unified physics
Time allowed: 1 hour 30 minutes
You must have:
• the Data, Formulae and Relationships Booklet
You can use:
• a scientific or graphical calculator
• a ruler (cm/mm)
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra
space use the lined page at the end of this booklet. The question numbers must
be clearly shown.
• Answer all the questions.
• Where appropriate, your answers should be supported with working. Marks
might be given for using a correct method, even if your answer is wrong.
INFORMATION
• The total mark for this paper is 70.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 20 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025 OCR is an exempt
[601/4743/X] DC Charity Turn over
(ST/JG) 360406/2
, 2
1 The Earth’s aurora is an atmospheric effect visible in the polar regions.
Electrons in the upper atmosphere initially move vertically downwards along one of the Earth’s
magnetic field lines. They are accelerated by an electric field.
These electrons collide with oxygen atoms causing atomic electrons to be excited to
higher energy levels. The atomic electrons then return to lower energy levels, releasing
photons of green light, red light and ultraviolet.
The accelerated electrons then travel horizontally through the atmosphere, before
travelling vertically along a different magnetic field line, and then completing the circuit
by travelling horizontally back to their starting point.
The situation is shown in Fig.
1.1. Fig. 1.1
electron flow
acceleration
region
20 000 km magnetic
field
aurora
electron flow
detector
not to scale
(a) The accelerated electrons are accelerated by electric fields parallel to the magnetic field lines.
The length of the acceleration region is 20000km and the electric field value is 0.2mV/m. The
electric field can be assumed to be uniform.
(i) Calculate the kinetic energy gained by the electrons as they pass through the electric field, in
joules.
kinetic energy = ..............................................J [3]
© OCR 2025
, 3
(ii) State and explain the direction of the electric field required to accelerate the electrons
downwards.
..........................................................................................................................................
................
..........................................................................................................................................
................
..........................................................................................................................................
................
. ........................................................................................................................... [2]
(b) A simplified energy level diagram for atomic oxygen is shown below.
energy (eV) 0
–9.4
–11.7
–13.6
not to scale
Determine the wavelength of the green light emitted.
Fully justify your answer.
wavelength = ..............................................m [4]
© OCR 2025 Turn over
, 4
(c) The horizontal current closest to the Earth produces a magnetic field which can be
detected at ground level.
With reference to Fig. 1.1, state and explain the direction of this magnetic field.
..........................................................................................................................................
................
..........................................................................................................................................
................
..........................................................................................................................................
................
. ........................................................................................................................... [2]
(d) Suggest two ways that the horizontal current may affect the atmosphere.
1 .......................................................................................................................................
................
..........................................................................................................................................
................
2 .......................................................................................................................................
................
..........................................................................................................................................
................
[2]
© OCR 2025
H556/03 Unified physics
Verified Question paper with Marking Scheme
Attached
Oxford Cambridge and RSA
Tuesday 17 June 2025 – Morning
A Level Physics A
H556/03 Unified physics
Time allowed: 1 hour 30 minutes
You must have:
• the Data, Formulae and Relationships Booklet
You can use:
• a scientific or graphical calculator
• a ruler (cm/mm)
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra
space use the lined page at the end of this booklet. The question numbers must
be clearly shown.
• Answer all the questions.
• Where appropriate, your answers should be supported with working. Marks
might be given for using a correct method, even if your answer is wrong.
INFORMATION
• The total mark for this paper is 70.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 20 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025 OCR is an exempt
[601/4743/X] DC Charity Turn over
(ST/JG) 360406/2
, 2
1 The Earth’s aurora is an atmospheric effect visible in the polar regions.
Electrons in the upper atmosphere initially move vertically downwards along one of the Earth’s
magnetic field lines. They are accelerated by an electric field.
These electrons collide with oxygen atoms causing atomic electrons to be excited to
higher energy levels. The atomic electrons then return to lower energy levels, releasing
photons of green light, red light and ultraviolet.
The accelerated electrons then travel horizontally through the atmosphere, before
travelling vertically along a different magnetic field line, and then completing the circuit
by travelling horizontally back to their starting point.
The situation is shown in Fig.
1.1. Fig. 1.1
electron flow
acceleration
region
20 000 km magnetic
field
aurora
electron flow
detector
not to scale
(a) The accelerated electrons are accelerated by electric fields parallel to the magnetic field lines.
The length of the acceleration region is 20000km and the electric field value is 0.2mV/m. The
electric field can be assumed to be uniform.
(i) Calculate the kinetic energy gained by the electrons as they pass through the electric field, in
joules.
kinetic energy = ..............................................J [3]
© OCR 2025
, 3
(ii) State and explain the direction of the electric field required to accelerate the electrons
downwards.
..........................................................................................................................................
................
..........................................................................................................................................
................
..........................................................................................................................................
................
. ........................................................................................................................... [2]
(b) A simplified energy level diagram for atomic oxygen is shown below.
energy (eV) 0
–9.4
–11.7
–13.6
not to scale
Determine the wavelength of the green light emitted.
Fully justify your answer.
wavelength = ..............................................m [4]
© OCR 2025 Turn over
, 4
(c) The horizontal current closest to the Earth produces a magnetic field which can be
detected at ground level.
With reference to Fig. 1.1, state and explain the direction of this magnetic field.
..........................................................................................................................................
................
..........................................................................................................................................
................
..........................................................................................................................................
................
. ........................................................................................................................... [2]
(d) Suggest two ways that the horizontal current may affect the atmosphere.
1 .......................................................................................................................................
................
..........................................................................................................................................
................
2 .......................................................................................................................................
................
..........................................................................................................................................
................
[2]
© OCR 2025
