The questions are on the waves test. Take it under real conditions before reading the mark scheme.
Quick answer: A wave is a repeating disturbance that carries energy from place to place without moving matter along with it. This mark scheme gives the model answers and the marks for the 8 questions of the grade 7 science test on waves, from wave terms to sound wavelength, with the equivalent answers to accept.
Use these model answers with the marking notes. Award method marks even when the final number is wrong, provided the formula and substitution are correct, and check that every answer has a sensible unit.
Level: Grade 7 science (Year 8 · Class 7) · Curriculum: MS-PS4-1
Question 1 Wave terms (3 marks)
- The length of one complete wave, such as crest to crest.
- The hertz (Hz).
- The amplitude.
Marking: 1 mark each.
Question 2 Types of wave (2 marks)
- Longitudinal.
- Transverse.
Marking: 1 mark each.
Question 3 Counting at the jetty (3 marks)
- f = N ÷ t = 36 ÷ 12 = 3.0 Hz.
- T = 1 ÷ 3.0 = 0.33 s.
Marking: (a) 1 mark for the formula or substitution, 1 for the answer with unit; (b) 1 mark.
Question 4 Ripple tank (3 marks)
- v = f × λ = 6.0 × 0.25 = 1.5 m/s.
- t = 0.90 ÷ 1.5 = 0.60 s.
Marking: (a) 1 mark method, 1 mark answer and unit; (b) 1 mark.
Question 5 Floating cork (2 marks)
The water particles only vibrate up and down around fixed positions. The wave transfers energy across the pond but does not carry the water or the cork along.Marking: 1 mark for vibration in place, 1 mark for energy moving but not matter.
Question 6 Reading two waves (3 marks)
- The amplitude of A is 2 cm.
- B repeats every 3 cm: 3 cm.
- B has the shorter wavelength, so at the same speed B has the higher frequency.
Marking: 1 mark each part.
Question 7 Two drum beats (2 marks)
The hard hit makes vibrations with a larger amplitude. A larger amplitude means the wave carries more energy, so the sound is louder.Marking: 1 mark for the larger amplitude, 1 mark for more energy giving a louder sound.
Question 8 Sound wavelength (2 marks)
λ = v ÷ f = 340 ÷ 170 = 2.0 m.Marking: 1 mark for rearranging or substituting, 1 mark for the answer with unit.
