6.6 Sound waves and hearing
9 exam questions worth 20 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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What is the approximate range of frequencies that a healthy young person can hear?
Choose one answer.
Correct Not quite: the answer is 20 Hz to 20 kHz
Mark scheme
B: 20 Hz to 20 kHz
Model answer
20 Hz to 20 kHz (B).
Explain why sound cannot travel through a vacuum.
Mark scheme
sound is passed on by vibrating particles (1); there are no particles in a vacuum to pass on the vibrations (1)
Model answer
Sound travels by particles passing on vibrations, and in a vacuum there are no particles.
A sound wave travels from air into water. State what happens to its frequency, speed and wavelength.
Mark scheme
frequency stays the same (1); speed increases (1); wavelength increases (1)
Model answer
The frequency stays the same, the speed increases and the wavelength gets longer.
Explain why sound travels faster in a solid than in a gas.
Mark scheme
the particles in a solid are closer together (1); so vibrations are passed on more quickly from particle to particle (1)
Model answer
In a solid the particles are close together and strongly bonded, so vibrations are passed on more quickly than in a gas, where the particles are far apart.
Describe how the appearance of a sound wave on an oscilloscope changes if the sound gets (a) louder, (b) higher in pitch.
Mark scheme
(a) the amplitude of the wave increases (1); (b) there are more waves in the same time / the frequency increases (1)
Model answer
(a) The waves are taller (greater amplitude). (b) There are more waves in the same time (greater frequency).
Describe how the ear converts a sound wave into signals that the brain can interpret.
Mark scheme
sound makes the eardrum vibrate (1); the vibrations pass through the ossicles (small bones) which amplify them (1); the vibrations pass into the cochlea, which converts them into electrical signals (1); the signals pass along the auditory nerve to the brain (1)
Model answer
The sound waves make the eardrum vibrate. The vibrations pass through the ossicles, which amplify them, to the cochlea, which converts them into electrical signals. These are sent along the auditory nerve to the brain.
The speed of sound in air is 330 m/s. Calculate the wavelength of a sound of frequency 660 Hz.
Mark scheme
λ = v ÷ f = 330 ÷ 660 (1); 0.50 m (1)
Model answer
λ = v / f = 330 / 660 = 0.50 m.
Sound travels at 1500 m/s in water. A sound of frequency 3000 Hz travels in the water. Calculate its wavelength.
Mark scheme
λ = v ÷ f = 1500 ÷ 3000 (1); 0.50 m (1)
Model answer
λ = v / f = 1500 / 3000 = 0.50 m.
State why humans cannot hear the sounds that bats use to find their way.
Mark scheme
bats use ultrasound / frequency above 20 kHz (1); which is above the range of human hearing (1)
Model answer
Bats use ultrasound, which has a frequency above 20 kHz, higher than the range that humans can hear.
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