Heat Transfer Miscellaneous
 Thermal conductivity is lower for

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NA
Correct Option: B
NA
 Match the property with their units
Property Units A. Bulk modulus 1. W/s B. Thermal conductivity 2. N/m^{2} C. Heat transfer coefficient 3. N/m^{3} D. Heat flow rate 4. W 5. W/mK 6. W/m^{2}K

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NA
Correct Option: B
NA
 For a given heat flow and for the same thickness, the temperature drop across the material will be maximum for

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dT ∝ 1 K
So, glass wool has minimum thermal conductivity and therefore maximum temperature difference.Correct Option: C
dT ∝ 1 K
So, glass wool has minimum thermal conductivity and therefore maximum temperature difference.
 Match Group with Group B:
Group A Group B A: Biot number 1: Ratio of buoyancy to viscous force B: Grashoff number 2: Ratio of inertia force to viscous force C: Prandtl number 3: Ratio of momentum to thermal diffusivities D: Reynolds number 4: Ratio of internal thermal resistance to boundary layer thermal resistance

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NA
Correct Option: A
NA
 The temperature variation under steady heat conduction across a composite slab of two materials with thermal conductivities k_{1} and k_{2} is shown in figure then, which one of the following statements holds?

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Q = KA dt dx where Slope = dt = Q dx KA
i.e., slope is more for less value of K, thereforedt > dt dx _{Ⅰ material} dx _{Ⅱ material}
∴ K_{1} < K_{2}Correct Option: A
Q = KA dt dx where Slope = dt = Q dx KA
i.e., slope is more for less value of K, thereforedt > dt dx _{Ⅰ material} dx _{Ⅱ material}
∴ K_{1} < K_{2}