AQA GCSE Combined Science: Trilogy Physics Paper 2 (Higher), 2020: Question 5

Mark scheme

Show the mark scheme

AO / Spec.

Question Answers Extra information Mark

Ref.

05.1 X-rays are absorbed by bone 1 AO1

6.6.2.4

but can pass through flesh ignore skin 1

05.2 taking lots of X-rays would give a 1 AO3

large dose 6.6.2.3

which would increase the 1

radiographer’s risk

the screen absorbs some of the allow screen reduces the 1

X-rays risk/dose received by the

radiographer

05.3 electrical current / oscillations in 1 AO1

the transmitter producing radio 6.6.2.3

waves

radio waves are absorbed by the 1

receiver inducing electrical

current / oscillations in the

receiver

at the same frequency 1

if no other mark is awarded, allow

1 mark for radio waves transfer

information/energy through the

air

Total 8

How to answer it

Low Demand

X-rays, body imaging and radio waves

What this question tests

You need to know how X-rays create contrast in the body, why repeated exposure is risky, and how radio waves transfer signals between a transmitter and receiver. The marks are mainly for using key physics ideas clearly: absorption, protection from radiation, and wave-induced currents.

Question 05.1 — Why X-rays can show bones

Explain why X-rays can be used to produce images of bones inside the body. [2 marks]

✅ Correct answer

X-rays are absorbed by bone but can pass through flesh.

💡 Key knowledge

Bone absorbs more X-rays than soft tissue.
Soft tissue lets more X-rays through.
This difference in absorption creates an image with contrast.

🧠 Exam technique

To get both marks, mention two contrasting materials: bone and flesh/soft tissue.
Use the idea of absorption and passing through.
Keep it short and direct: one sentence can score both marks.

❌ Common errors

Saying X-rays are “seen” by bone is too vague.
Talking about skin instead of flesh/soft tissue is not needed.
Writing that bones “reflect” X-rays is incorrect.

How marks are awarded: 1 mark for stating that X-rays are absorbed by bone, and 1 mark for stating that X-rays pass through flesh/soft tissue.

Question 05.2 — Why the radiographer stands behind a protective screen

Explain why the radiographer stands behind a protective screen when taking an X-ray image. [3 marks]

✅ Correct answer

The radiographer takes many X-rays each day, so they would receive a large dose. This would increase their risk of harm, so the screen absorbs some of the X-rays and reduces the dose they receive.

💡 Key knowledge

Radiation dose adds up if exposure happens repeatedly.
Higher dose means higher risk of damage, including cancer.
A protective screen reduces the amount of X-rays reaching the radiographer.

🧠 Exam technique

For 3 marks, build a chain of reasoning: many X-rays → large dose → higher risk → screen reduces exposure.
Use the table data to support the idea that larger doses cause more serious effects.
Link the screen to absorption or reduction in dose.

❌ Common errors

Only saying “for protection” is too vague.
Missing the idea that the radiographer is exposed many times a day loses marks.
Writing that the screen “blocks all radiation” is too absolute unless clearly qualified.

📐 Calculations / data use

No calculation is needed here, but you should use the dose information carefully: a patient receives 0.5 mSv in one X-ray, but a radiographer may receive many doses across the day. Repeated exposure is the key risk.

How marks are awarded: credit is given for stating that repeated X-rays give a large dose, that this increases the radiographer’s risk, and that the screen absorbs/reduces some of the X-rays.

Question 05.3 — How radio waves produce a signal in a receiver

Explain how electrical signals in the transmitter produce a signal in the receiver. [3 marks]

✅ Correct answer

Electrical current in the transmitter produces radio waves. The radio waves are absorbed by the receiver, inducing an electrical current in it at the same frequency.

💡 Key knowledge

In a transmitter, an alternating electrical current creates radio waves.
The waves transfer energy/information through the air.
In the receiver, the waves induce an alternating current at the same frequency.

🧠 Exam technique

Use the sequence: transmitter current → radio waves → receiver current.
To reach full marks, include the idea that the receiver current is at the same frequency.
If you are unsure, a basic statement that radio waves carry information through the air can gain partial credit, but the full chain is better.

❌ Common errors

Saying the receiver “gets electricity from the transmitter directly” is wrong.
Forgetting the role of radio waves in between loses marks.
Leaving out “same frequency” is a common reason top answers lose the final mark.

📐 Calculations / wave detail

No numerical calculation is required. However, the exam wants the physics of wave transfer: the transmitter makes radio waves, and the receiver detects them by inducing a current. The frequency should stay the same.

How marks are awarded: 1 mark for current/oscillations in the transmitter producing radio waves, 1 mark for the receiver absorbing the radio waves and inducing current/oscillations, and 1 mark for stating the same frequency.

Quick revision summary

✅ Must-remember facts

X-rays: absorbed by bone, pass through soft tissue.
Protective screens reduce radiation dose.
Repeated exposure increases risk.
Transmitter current makes radio waves.
Receiver absorbs radio waves and produces current at the same frequency.

🧠 Top-scoring habits

Use key terms exactly: absorbed, dose, induce, frequency.
Answer in linked steps, not disconnected facts.
When a table is given, use it to support your explanation.

Topics

Physics · P6: Waves · P4: Atomic Structure