AQA GCSE Physics Physics Paper 2 (Foundation), November 2020: Question 4

9 marks · Standard Demand difficulty · Short Answer

Identify electromagnetic waves used for communications, name optical physics terms, draw reflected rays, state properties of optical fibres, and describe the interaction of light with filters and objects.

Practise this question

Question

$A multi-part physics question about electromagnetic waves and light. Part 04.1 asks to tick two boxes for parts of the EM spectrum used for communications from gamma rays, microwaves, radio waves, ultraviolet, and X-rays. Figure 5 shows a ray of light travelling inside an optical fibre and hitting a vertical dashed line representing the normal. Parts 04.2, 04.3, and 04.4 ask for the name of the dotted line, to draw the reflected ray on Figure 5, and to suggest the property optical fibres must have to bend. Part 04.5 asks to complete sentences about light interacting with filters and objects using words from a provided box: absorbed, reflected, refracted, transmitted.$

Question text

04.1 Visible light is used for communications.

Which other parts of the electromagnetic spectrum are used for communications?

[2 marks]

Tick ( ) two boxes.

Gamma rays

Microwaves

Radio waves

Ultraviolet

X-rays

Figure 5 shows a ray of light in an optical fibre.

Figure 5

04.2 What is the name given to the dotted line on Figure 5?

[1 mark]

04.3 Where the ray of light touches the edge of the optical fibre it is reflected.

Draw the reflected ray on Figure 5.

[2 marks]

04.4 Optical fibres need to be able to bend around corners without breaking.

Suggest the property that optical fibres must have to allow them to bend around

corners.

[1 mark]

04.5 The appearance of visible light can change when it interacts with different objects.

Complete the sentences.

Choose the answers from the box.

Each answer may be used once, more than once or not at all.

[3 marks]

absorbed reflected refracted transmitted

When white light is incident on a green filter, only green light passes through the filter.

This is because green light is by the filter.

All other colours of light are by the filter.

When red light shines on a blue object the red light is .

Mark scheme

Show the mark scheme

Question 4

AO /

Question Answers Extra information Mark

Spec. Ref.

04.1 Microwaves 1 AO1

4.6.2.4

Radio waves 1

04.2 normal 1 AO1

4.6.1.3

04.3 reflected ray drawn to the right ignore arrows 1 AO2

of the normal 4.6.1.3

correct ray of light drawn using a 1

ruler with i = r

04.4 they need to be flexible ignore bendy / ductile / 1 AO3

malleable / elastic 4.6.2.4

04.5 transmitted 1 AO1

4.6.2.6

absorbed 1

Total 9

How to answer it

Electromagnetic Waves and Optical Fibres

What this question tests

This question assesses your knowledge of the electromagnetic spectrum (uses of different waves), reflection and ray diagrams (specular reflection and the normal), the physical properties required for optical fibres, and the interaction of visible light with filters and colored objects (absorption, transmission, and reflection).

Question 04.1 [2 marks]

Electromagnetic Spectrum for Communications

✅ Correct Answers

Microwaves (Tick)
Radio waves (Tick)

1 mark per correct tick. Max 2 marks. If more than two boxes are ticked, deduct one mark for each incorrect tick.

💡 Key Knowledge

Microwaves: Used for satellite communications and mobile phones because they can pass easily through the Earth's atmosphere.
Radio waves: Used for television and radio broadcasting because their long wavelengths can diffract around hills and obstacles.

Question 04.2 [1 mark]

Ray Diagrams: Labelling the Dotted Line

✅ Correct Answer

normal

1 mark for naming the line correctly.

💡 Key Knowledge

The normal is an imaginary line drawn at a right angle (90 degrees) to the boundary or surface where a light ray strikes.
All angles of incidence and reflection are measured relative to this normal line, not the surface itself.

Question 04.3 [2 marks]

Drawing a Reflected Ray

✅ Correct Answers

Reflected ray drawn to the right of the normal (inside the optical fibre boundary).
Correct ray of light drawn using a ruler showing angle of incidence equals angle of reflection (i = r).

1 mark for ray on the correct side of the normal; 1 mark for accurate drawing matching i = r using a ruler. Note: arrows on the ray are ignored.

🧠 Exam Technique

Always use a sharp pencil and a ruler for ray diagrams. Freehand lines often miss the angle marks.
Visually check that the angle the ray makes coming off the boundary matches the angle it went in with (symmetric across the normal).

Question 04.4 [1 mark]

Properties of Optical Fibres

✅ Correct Answer

They need to be flexible.

1 mark. Acceptable alternatives: "flexible". Note: Examiner report ignores "bendy", "ductile", "malleable", or "elastic".

❌ Common Errors

Students often write descriptive words like "stretchy" or "bendable". Stick to the precise scientific terminology required by the specification: flexible.

Question 04.5 [3 marks]

Interaction of Light with Objects and Filters

✅ Correct Answers

When white light hits a green filter, green light passes through because it is transmitted.
All other colours of light are absorbed by the filter.
When red light shines on a blue object, the red light is absorbed.

1 mark for each correct gap-fill. Total 3 marks.

💡 Key Knowledge

Colour filters work by absorbing specific wavelengths (colours) of light and transmitting only the colour of the filter itself.
Opaque objects appear a certain colour because they reflect that specific wavelength of light and absorb all other wavelengths. If a coloured light shines on an object that does not reflect that colour (e.g. red light on a blue object), the light is completely absorbed and the object looks black.

Topics

Physics · P6: Waves

Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 2 (Foundation), November 2020. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.