# Practice Test: Question Set - 07

**1. The value of the wavelength for maximum emissive power is given by**

- (A) Wien's law

- (B) Planck's law

- (C) Stefan's law

- (D) Fourier's law

**2. The heat of sun reaches to us according to**

- (A) Conduction

- (B) Convection

- (C) Radiation

- (D) None
of these

**3. Log mean temperature difference in case of counter flow compared to parallel flow will be**

- (A) Same

- (B) More

- (C) Less

- (D) Depends on other
factors

**4. Sensible heat factor is given by (where**

*S*.*H*. = Sensible heat, and*L*.*H*. = Latent heat)- (A)

*S.H/(S.H + L.H)*

- (B)

*(S.H + L.H) /S.H*

- (C)

*(L.H - S.H)/S.H*

- (D)

*S.H/(L.H - S.H)*

**5. The energy distribution of an ideal reflector at higher temperatures is largely in the range of**

- (A) Shorter wavelength

- (B) Longer wavelength

- (C) Remain same at all
wavelengths

- (D) Wavelength has
nothing to do with it

**6. The most commonly used method for the design of duct size is the**

- (A) Velocity
reduction method

- (B) Equal
friction method

- (C) Static
regains method

- (D) Dual
or double method

**7. Total emissivity of polished silver compared to black body is**

- (A) Same

- (B) Higher

- (C) More or less same

- (D) Very much lower

**8. The rate of heat flow through a body is**

*Q = [kA (T₁ - T₂)]/x*. The term*x**/kA*is known as- (A) Thermal
coefficient

- (B) Thermal
resistance

- (C) Thermal
conductivity

- (D) None
of these

**9. According to Stefan Boltzmann law, ideal radiators emit radiant energy at a rate proportional to**

- (A) Absolute temperature

- (B) Square of temperature

- (C) Fourth power of
absolute temperature

- (D) Fourth power of
temperature

**10. The transfer of heat by molecular collision is known as**

- (A) Conduction

- (B) Convection

- (C) Radiation

- (D) None
of these

**11. Which of the following property of air does not increase with rise in temperature?**

- (A) Thermal conductivity

- (B) Thermal diffusivity

- (C) Density

- (D) Dynamic viscosity

**12. The expression**

*Q**= ρ AT*is called^{4}- (A) Fourier
equation

- (B) Stefan-Boltzmann
equation

- (C) Newton
Reichmann equation

- (D) Joseph-Stefan
equation

**13. The unit of Stefan Boltzmann constant is**

- (A) watt/cm² °K

- (B) watt/cm⁴ °K

- (C) watt²/cm °K⁴

- (D) watt/cm² °K⁴

**14. The unit of Stefan-Boltzmann constant is**

- (A) Watt/mK

- (B) Watt/m²K²

- (C) Watt/m²K

^{4}

- (D) Watt/mK²

**15. In free convection heat transfer, Nusselt number is function of**

- (A) Grashoff number and Reynold number

- (B) Grashoff number and
Prandtl number

- (C) Prandtl number and
Reynold number

- (D) Grashoff number, Prandtl
number and Reynold number

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