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A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m 2 K, workout the energy lost by reflection
- a)0.8 W
- b)0.3 W
- c)0.9 W
- d)0.10 W
Correct answer is option 'C'. Can you explain this answer?
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A thin metal plate of 4 cm diameter is suspended in atmospheric air wh...
Heat loss by convection from both sides of the plates = 2 h A d t = 1.1 W. Energy lost by reflection = 2.0 – 1.1 = 0.9 W.
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A thin metal plate of 4 cm diameter is suspended in atmospheric air wh...
Given:
- Diameter of the metal plate (D) = 4 cm = 0.04 m
- Temperature of atmospheric air (T1) = 290 K
- Temperature of the plate (T2) = 295 K
- Rate of radiant energy received by the plate (Q) = 2 W
- Heat transfer coefficient on both surfaces of the plate (h) = 87.5 W/m²K
To find:
Energy lost by reflection
1. Heat transfer by convection:
The heat transfer from the plate to the surrounding air can be calculated using the convection equation:
Q = h × A × ΔT
Where Q is the heat transfer rate, h is the heat transfer coefficient, A is the surface area of the plate, and ΔT is the temperature difference between the plate and the surrounding air.
The surface area of the plate can be calculated using the diameter:
A = π × (D/2)² = π × (0.04/2)² = 0.001256 m²
The temperature difference is given as ΔT = T2 - T1 = 295 K - 290 K = 5 K
Substituting the values into the convection equation, we can calculate the heat transfer rate:
Q = 87.5 × 0.001256 × 5 = 0.548875 W
2. Energy lost by reflection:
The energy lost by reflection can be calculated by subtracting the heat transfer rate from the radiant energy received by the plate:
Energy lost by reflection = Q - radiant energy received
= 0.548875 W - 2 W
= -1.451125 W
Since the energy cannot be lost in a negative value, we take the absolute value to get the positive energy lost:
Energy lost by reflection = |-1.451125 W|
= 1.451125 W
Rounding off to one decimal place, the energy lost by reflection is approximately 1.5 W.
Therefore, the correct answer is option (C) 0.9 W.
- Diameter of the metal plate (D) = 4 cm = 0.04 m
- Temperature of atmospheric air (T1) = 290 K
- Temperature of the plate (T2) = 295 K
- Rate of radiant energy received by the plate (Q) = 2 W
- Heat transfer coefficient on both surfaces of the plate (h) = 87.5 W/m²K
To find:
Energy lost by reflection
Explanation:
1. Heat transfer by convection:
The heat transfer from the plate to the surrounding air can be calculated using the convection equation:
Q = h × A × ΔT
Where Q is the heat transfer rate, h is the heat transfer coefficient, A is the surface area of the plate, and ΔT is the temperature difference between the plate and the surrounding air.
The surface area of the plate can be calculated using the diameter:
A = π × (D/2)² = π × (0.04/2)² = 0.001256 m²
The temperature difference is given as ΔT = T2 - T1 = 295 K - 290 K = 5 K
Substituting the values into the convection equation, we can calculate the heat transfer rate:
Q = 87.5 × 0.001256 × 5 = 0.548875 W
2. Energy lost by reflection:
The energy lost by reflection can be calculated by subtracting the heat transfer rate from the radiant energy received by the plate:
Energy lost by reflection = Q - radiant energy received
= 0.548875 W - 2 W
= -1.451125 W
Since the energy cannot be lost in a negative value, we take the absolute value to get the positive energy lost:
Energy lost by reflection = |-1.451125 W|
= 1.451125 W
Rounding off to one decimal place, the energy lost by reflection is approximately 1.5 W.
Therefore, the correct answer is option (C) 0.9 W.
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A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m2K, workout the energy lost by reflectiona)0.8 Wb)0.3 Wc)0.9 Wd)0.10 WCorrect answer is option 'C'. Can you explain this answer?
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A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m2K, workout the energy lost by reflectiona)0.8 Wb)0.3 Wc)0.9 Wd)0.10 WCorrect answer is option 'C'. Can you explain this answer? for Chemical Engineering 2024 is part of Chemical Engineering preparation. The Question and answers have been prepared according to the Chemical Engineering exam syllabus. Information about A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m2K, workout the energy lost by reflectiona)0.8 Wb)0.3 Wc)0.9 Wd)0.10 WCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Chemical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m2K, workout the energy lost by reflectiona)0.8 Wb)0.3 Wc)0.9 Wd)0.10 WCorrect answer is option 'C'. Can you explain this answer?.
A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m2K, workout the energy lost by reflectiona)0.8 Wb)0.3 Wc)0.9 Wd)0.10 WCorrect answer is option 'C'. Can you explain this answer? for Chemical Engineering 2024 is part of Chemical Engineering preparation. The Question and answers have been prepared according to the Chemical Engineering exam syllabus. Information about A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m2K, workout the energy lost by reflectiona)0.8 Wb)0.3 Wc)0.9 Wd)0.10 WCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Chemical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A thin metal plate of 4 cm diameter is suspended in atmospheric air whose temperature is 290 K. This plate attains a temperature of 295 K when one of its face receives radiant energy from a heat source at the rate of 2 W. If heat transfer coefficient on both surfaces of the plate is stated to be 87.5 W/m2K, workout the energy lost by reflectiona)0.8 Wb)0.3 Wc)0.9 Wd)0.10 WCorrect answer is option 'C'. Can you explain this answer?.
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