Waves
11 Grade 10 General Science questions on Waves, with worked marking schemes. 11 questions are available on this topic in full.
Question 1
4 marksExplain the meaning of each of the following terms as used in waves, and state the SI unit of each.
(a) Wavelength (2 marks)
(b) Frequency (2 marks)
(4 marks)
Marking scheme for this question
Create a free account to see itQuestion 2
5 marksStrong sea waves frequently hit coastal towns such as Lamu, Malindi and Mombasa.
(a) State three effects of strong sea waves on coastal communities and their environment. (3 marks)
(b) Outline two measures that can reduce these effects. (2 marks)
(5 marks)
Marking scheme
(a) Any three of the following, 1 mark each (3 marks): - Coastal (beach) erosion that destroys beaches, homes and hotels - Damage to infrastructure such as roads, sea walls, jetties and port facilities - Flooding of low-lying areas near the shore - Destruction of marine habitats such as coral reefs, sea grass and mangroves - Capsizing of boats and loss of fishing days, reducing fishermen's income - Disruption of shipping and port operations - Salt water entering wells and farmland - Loss of income from tourism (b) Any two of the following, 1 mark each (2 marks): - Building sea walls, breakwaters or groynes to absorb wave energy - Planting and conserving mangroves along the shoreline - Protecting coral reefs, which break the force of waves - Restricting construction close to the shoreline (setback rules) - Using weather forecasts and early warnings from the meteorological department to keep boats ashore and evacuate people - Beach nourishment (replacing eroded sand)
Question 3
5 marksPeople living near a church in a village notice that the church bell is heard much more clearly at night than during the day.
(a) Explain this observation. (3 marks)
(b) Draw a labelled sketch showing the path of the sound from the bell to a distant listener at night. (2 marks)
(5 marks)
Marking scheme
(a) (3 marks) - At night the ground cools quickly, so the air near the ground is cooler than the air higher up (1 mark) - Sound travels more slowly in cool air than in warm air (1 mark) - The sound is therefore refracted (bent) downwards towards the ground, so more of it reaches the distant listener (1 mark) (Accept the reverse argument for daytime: warm air near the ground bends sound upwards, away from listeners.) (b) (2 marks) - Sound paths from the bell drawn curving downwards towards the ground and the listener (1 mark) - Labels showing warm air above and cool air near the ground (1 mark)
Question 4
4 marksA fishing boat off the coast of Malindi uses an echo sounder to find the depth of the sea. A sound pulse sent straight down from the boat returns to it 0.4 s later. The speed of sound in sea water is 1500 m/s.
(a) Calculate the depth of the sea below the boat. (3 marks)
(b) State one other use of echoes in day-to-day life. (1 mark)
(4 marks)
Marking scheme for this question
Create a free account to see itQuestion 5
1 markWhich of the following best describes the amplitude of a wave?
A. The maximum displacement of a particle from its rest position
B. The total distance moved by a particle during one full oscillation
C. The vertical distance from a crest down to the trough next to it
D. The greatest distance that the wave travels away from its source
(1 mark)
Marking scheme for this question
Create a free account to see itQuestion 6
3 marksA radio station in Nairobi broadcasts on a frequency of 98.4 MHz. Radio waves travel at 3.0 × 10⁸ m/s. Calculate the wavelength of the radio waves from the station. (3 marks)
(3 marks)
Marking scheme for this question
Create a free account to see itQuestion 7
1 markA learner doubles the frequency of a signal generator connected to a loudspeaker in the laboratory. What happens to the wavelength of the sound produced in air?
A. It stays the same, since only the speed of the wave changes
B. It falls to a quarter of its value, since the medium resists it
C. It doubles, since wavelength is proportional to frequency
D. It halves, since the speed in the medium stays constant
(1 mark)
Marking scheme for this question
Create a free account to see itQuestion 8
1 markWhich statement correctly describes what a wave does as it travels through a medium?
A. It carries energy without a net transfer of the medium
B. It carries energy only when it moves through a solid material
C. It carries matter from the source to every point it reaches
D. It carries energy and matter together at the speed of light
(1 mark)
Marking scheme for this question
Create a free account to see itQuestion 9
6 marksDescribe how a group of learners can determine the speed of sound in air using the echo method on the school compound. (6 marks)
(6 marks)
Marking scheme
Any six of the following, 1 mark each (6 marks): - Choose a tall, flat wall (e.g. a classroom block) in an open area with no other reflecting surfaces nearby, away from roads for safety - Measure a distance d (at least about 50 m) from the wall using a tape measure and stand at that point - One learner claps two wooden blocks (or hands) and listens for the echo - Adjust the rate of clapping until each clap coincides with the echo of the previous clap - A second learner starts a stopwatch on one clap and counts a number of intervals, e.g. 20, then stops the stopwatch - Time for one interval t = total time ÷ number of intervals; this is the time for sound to travel to the wall and back - The sound travels a total distance of 2d in time t - Speed of sound v = 2d/t - Repeat the experiment (or change roles/distance) and find the average value
Question 10
1 markRoad studs, commonly called cat's eyes, are fitted along the middle of many Kenyan highways. They help drivers at night mainly because they
A. reflect light from headlights back towards the driver
B. diffract headlight beams around sharp bends ahead of the car
C. absorb sunlight by day and then glow throughout the night
D. refract street lighting sideways across the full road width
(1 mark)
Marking scheme for this question
Create a free account to see itQuestion 11
1 markA wave travels a distance of 60 m in 4 s. If its wavelength is 3 m, what is its frequency?
A. 5 Hz
B. 20 Hz
C. 45 Hz
D. 0.2 Hz
(1 mark)
Marking scheme for this question
Create a free account to see it8 more marking schemes are on this page. A free account opens all of them, and lets you build your own paper on the topics you have actually taught, laid out in KNEC format with its full marking scheme.
Create a free account