The questions are on the reflection of light test. Take it under real conditions before reading the mark scheme.
Quick answer: Light is reflected, refracted or absorbed when it meets matter. This mark scheme gives the model answers and the marks for the 8 questions of the grade 7 science test on reflection of light, from key terms to dark clothes, with the equivalent answers to accept.
Use these model answers with the marking notes. Give method marks when the working is correct even if the final number is wrong, and check that angles are taken from the normal and that every answer has its unit.
Level: Grade 7 science (Year 8 · Class 7) · Curriculum: MS-PS4-2
Question 1 Key terms (3 marks)
- A line drawn at right angles to the surface at the point where the ray hits.
- The angle of incidence equals the angle of reflection.
- Refraction.
Marking: 1 mark each.
Question 2 Ray at a mirror (3 marks)
- i = 90° – 35° = 55°.
- r = i = 55°.
- 55° + 55° = 110°.
Marking: 1 mark each part.
Question 3 Mirror and image (3 marks)
- 1.8 m behind the mirror.
- 1.8 + 1.8 = 3.6 m.
- New distance from mirror = 2.4 m, so 2.4 + 2.4 = 4.8 m.
Marking: 1 mark each part.
Question 4 Light entering a block (3 marks)
- It bends towards the normal.
- Light travels more slowly in glass than in air. The change of speed at an angle makes the ray change direction towards the normal.
Marking: (a) 1 mark; (b) 1 mark for slower in glass, 1 mark for link between speed change and direction change.
Question 5 Rough and smooth (2 marks)
The rough wall gives diffuse reflection, scattering rays in all directions, so light reaches every viewer. The smooth mirror gives regular reflection in one direction, so the image is seen only where the reflected rays go.Marking: 1 mark for diffuse scattering by the wall, 1 mark for regular reflection by the mirror.
Question 6 A red book (2 marks)
White light contains all colours. The cover reflects mostly red light into the eye and absorbs the other colours.Marking: 1 mark for reflects red, 1 mark for absorbs the other colours.
Question 7 Sunlight to Earth (2 marks)
t = d ÷ v = 1.5 × 10¹¹ ÷ 3.0 × 10⁸ = 500 s (about 8.3 minutes).Marking: 1 mark for the substitution, 1 mark for the answer with unit.
Question 8 Dark clothes (2 marks)
Black cloth absorbs most of the light energy that hits it, which warms the cloth. White cloth reflects most of the light, so it absorbs less energy.Marking: 1 mark for black absorbs more, 1 mark for white reflects more.
