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A sound wave produces a maximum increase in pressure on an ear of 2.5 × 10^3 N m⁻² - AQA - A-Level Physics - Question 2 - 2020 - Paper 6
Question 2
A sound wave produces a maximum increase in pressure on an ear of 2.5 × 10^3 N m⁻². This causes a maximum increase in pressure in the fluid of the inner ear of 5.0 ... show full transcript
Worked Solution & Example Answer:A sound wave produces a maximum increase in pressure on an ear of 2.5 × 10^3 N m⁻² - AQA - A-Level Physics - Question 2 - 2020 - Paper 6
Step 1
0.2.1 Explain how the ossicles contribute to this increase in pressure in the fluid of the inner ear.
Answer
The ossicles, which are small bones in the middle ear, act as levers that amplify sound pressure. When sound waves create vibrations in the tympanic membrane, these vibrations are transferred to the ossicles. Due to their lever action, the ossicles increase the force exerted on the oval window, thereby increasing the pressure in the fluid of the inner ear. This amplification is crucial as it allows the sound waves to overcome the impedance of the fluid in the inner ear.
Step 2
0.2.2 Calculate the area, in m², of the oval window.
Answer
To find the area of the oval window, we first calculate the area of the tympanic membrane (which is a circle) using the formula:
A = rac{ ext{π}d^2}{4}
Given that the diameter (d) is 1.0 cm, we convert this to meters:
Now substituting into the area formula:
A = rac{ ext{π} (0.01)^2}{4} \ \\ = rac{ ext{π} (0.0001)}{4} \ \\ = rac{3.14 imes 0.0001}{4} \ \\ = 7.85 imes 10^{-5} ext{ m}^2
Therefore, the area of the oval window is approximately .