Oxford Cambridge and RSA - 2025
Tuesday 17 June 2025 – Morning
A Level Physics A
H556/03 Unified physics
Time allowed: 1 hour 30 minutes
(Verified Question Paper With Mark
Scheme Combined June 2025)
, 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
magnetic field
20 000 km
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 20 000 km and the electric field value is 0.2 mV
/ 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.
© OCR Turn over
2025
Tuesday 17 June 2025 – Morning
A Level Physics A
H556/03 Unified physics
Time allowed: 1 hour 30 minutes
(Verified Question Paper With Mark
Scheme Combined June 2025)
, 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
magnetic field
20 000 km
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 20 000 km and the electric field value is 0.2 mV
/ 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.
© OCR Turn over
2025
