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A brass scale of a barometer gives correct reading at 0°C. αBrass = 0.00002/°C. The barometer reads 75 cm at 27°C. The atmospheric pressure at 0°C is
  • a)
    74.20 cm
  • b)
    74.62 cm
  • c)
    74.92 cm
  • d)
    75.04 cm
Correct answer is option 'C'. Can you explain this answer?
Most Upvoted Answer
A brass scale of a barometer gives correct reading at 0°C. αBrass = 0...
Suppose the correct barometer height at 0°C is (l0, then
l0 + Δl = 75
or l0 +75 x (αHgb) x 27 = 75
or l0 + 75 x (0.6 x 10-4 - 0.2 x 10-4) x 27 = 75
∴ l0 = 74.92 cm
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Community Answer
A brass scale of a barometer gives correct reading at 0°C. αBrass = 0...
To solve this problem, we need to consider the expansion of the brass scale and how it affects the reading on the barometer.

1. Understanding the problem:
- The brass scale of the barometer gives correct readings at 0°C.
- The coefficient of linear expansion for brass (αBrass) is given as 0.00002/°C.
- The barometer reads 75 cm at 27°C.
- We need to find the atmospheric pressure at 0°C.

2. Calculating the expansion of the brass scale:
- The change in length of the brass scale can be calculated using the formula: ΔL = αL₀ΔT
where ΔL is the change in length, α is the coefficient of linear expansion, L₀ is the initial length, and ΔT is the change in temperature.
- Here, the initial length of the scale (L₀) is 75 cm and the change in temperature (ΔT) is 27°C.
- Substituting the values, we get: ΔL = (0.00002/°C)(75 cm)(27°C)
- Simplifying, we find: ΔL = 0.0405 cm

3. Adjusting the barometer reading:
- Since the brass scale expands with temperature, the length of the scale increases as the temperature rises.
- Therefore, the barometer reading at 27°C includes the expansion of the scale.
- To find the actual atmospheric pressure at 0°C, we need to subtract the expansion of the scale from the given reading at 27°C.
- The corrected length of the scale at 27°C is: L_corrected = L_reading - ΔL
- Substituting the values, we have: L_corrected = 75 cm - 0.0405 cm = 74.9595 cm

4. Converting the corrected length to atmospheric pressure:
- The atmospheric pressure is directly proportional to the height of the mercury column in the barometer.
- Therefore, we can say that the atmospheric pressure at 0°C is directly proportional to the corrected length of the scale at 27°C.
- Let's assume the atmospheric pressure at 0°C is P₀.
- Using the proportional relationship, we can write: P₀/P_reading = L_corrected/L_reading
- Substituting the values, we get: P₀/75 cm = 74.9595 cm/75 cm
- Simplifying, we find: P₀ = (74.9595 cm * 75 cm) / 75 cm = 74.9595 cm

5. Final answer:
- The atmospheric pressure at 0°C is approximately 74.92 cm, which corresponds to option 'C'.
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A brass scale of a barometer gives correct reading at 0°C. αBrass = 0.00002/°C. The barometer reads 75 cm at 27°C. The atmospheric pressure at 0°C isa)74.20 cmb)74.62 cmc)74.92 cmd)75.04 cmCorrect answer is option 'C'. Can you explain this answer?
Question Description
A brass scale of a barometer gives correct reading at 0°C. αBrass = 0.00002/°C. The barometer reads 75 cm at 27°C. The atmospheric pressure at 0°C isa)74.20 cmb)74.62 cmc)74.92 cmd)75.04 cmCorrect answer is option 'C'. Can you explain this answer? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about A brass scale of a barometer gives correct reading at 0°C. αBrass = 0.00002/°C. The barometer reads 75 cm at 27°C. The atmospheric pressure at 0°C isa)74.20 cmb)74.62 cmc)74.92 cmd)75.04 cmCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A brass scale of a barometer gives correct reading at 0°C. αBrass = 0.00002/°C. The barometer reads 75 cm at 27°C. The atmospheric pressure at 0°C isa)74.20 cmb)74.62 cmc)74.92 cmd)75.04 cmCorrect answer is option 'C'. Can you explain this answer?.
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