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Three bodies A , B and C have equal surf...

Three bodies `A , B` and `C` have equal surface area and thermal emissivities in the ratio `e_(A) : e_(B) : e_(C) = 1 : (1)/(2): (1)/(4)`. All the three bodies are radiating at same rate. Their wavelengths corresponding to maximum intensity are `alpha_(A), alpha_(B)` and `alpha_(C)` respectively and their temperatures are `T_(A) , T_(B)` and `T_(C)` on kelvin scale , then select the incorrect statement

A

`sqrt(T_(A)T_(C)) = T_(B)`

B

`sqrt(lambda_(A) lambda_(C)) = lambda_(B)`

C

`sqrt(e_(A) T_(A)) sqrt(e_(C)T_(C)) = e_(B)T_(B)`

D

`sqrt(e_(A)lambda_(A)T_(A).e_(B)lambda_(B)T_(B)) = e_(C)lambda_(C)T_(C)`

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The correct Answer is:
To solve the problem, we need to analyze the relationship between the emissivities, temperatures, and the wavelengths corresponding to maximum intensity for the three bodies A, B, and C. ### Step-by-Step Solution: 1. **Understanding Emissivity and Power Radiated**: - The emissivities of bodies A, B, and C are given in the ratio: \[ e_A : e_B : e_C = 1 : \frac{1}{2} : \frac{1}{4} \] - Let’s denote: \[ e_A = 1, \quad e_B = \frac{1}{2}, \quad e_C = \frac{1}{4} \] 2. **Using Stefan-Boltzmann Law**: - The power radiated by each body can be expressed using the Stefan-Boltzmann Law: \[ P = e \sigma A T^4 \] - Since all three bodies are radiating at the same rate, we can write: \[ e_A \sigma T_A^4 = e_B \sigma T_B^4 = e_C \sigma T_C^4 \] 3. **Setting Up the Equations**: - From the above, we can simplify: \[ T_A^4 = e_B \cdot T_B^4 / e_A \] \[ T_B^4 = e_C \cdot T_C^4 / e_B \] - Substituting the emissivity values: \[ T_A^4 = \frac{1/2}{1} T_B^4 = \frac{1}{2} T_B^4 \] \[ T_B^4 = \frac{1/4}{1/2} T_C^4 = \frac{1}{2} T_C^4 \] 4. **Relating Temperatures**: - From \(T_A^4 = \frac{1}{2} T_B^4\), we get: \[ T_A = \left(\frac{1}{2}\right)^{1/4} T_B = \frac{T_B}{\sqrt[4]{2}} \] - From \(T_B^4 = \frac{1}{2} T_C^4\), we get: \[ T_B = \left(\frac{1}{2}\right)^{1/4} T_C = \frac{T_C}{\sqrt[4]{2}} \] 5. **Finding Relationships**: - Now substituting back, we can express \(T_A\) in terms of \(T_C\): \[ T_A = \frac{T_C}{\sqrt[4]{2} \cdot \sqrt[4]{2}} = \frac{T_C}{\sqrt{2}} \] 6. **Wavelengths of Maximum Intensity**: - The wavelengths corresponding to maximum intensity are given by Wien's displacement law: \[ \lambda_{max} \propto \frac{1}{T} \] - Thus, we have: \[ \alpha_A \propto \frac{1}{T_A}, \quad \alpha_B \propto \frac{1}{T_B}, \quad \alpha_C \propto \frac{1}{T_C} \] - Substituting the temperature relationships: \[ \alpha_A \propto \sqrt{2} \cdot \alpha_C \] \[ \alpha_B \propto \sqrt[4]{2} \cdot \alpha_C \] 7. **Conclusion**: - The incorrect statement can be identified by checking the relationships derived above. The relationships between the wavelengths and temperatures must hold true based on the derived equations.

To solve the problem, we need to analyze the relationship between the emissivities, temperatures, and the wavelengths corresponding to maximum intensity for the three bodies A, B, and C. ### Step-by-Step Solution: 1. **Understanding Emissivity and Power Radiated**: - The emissivities of bodies A, B, and C are given in the ratio: \[ e_A : e_B : e_C = 1 : \frac{1}{2} : \frac{1}{4} ...
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