Q.no 11. Controlling heat transfer film co-efficient is the one, which offers __________resistance to the heat transfer.
A : No
B : The least
C : The largest
D : lower
Q.no 12. Solid angle is measured in
A : Radian
B : Ste-radian
C : Degree
D : None of these
Q.no 13. For perfectly black body, the reflectivity is equal to……
A : One
B : Zero
C : Infinity
D : None of these
Q.no 14. In the equation Q = UAΔt; Δt is
A : geometric mean temperature difference.
B : arithmetic mean temperature difference.
C : logarithmic mean temperature difference.
D : difference of average bulk temperatures of hot and cold fluids.
Q.no 15. In diffuse reflection the angle of
A : Incident # Reflection
B : Absorption = Transmittion
C : Incident = Reflection
D : None of these
Q.no 16. Heat flux is the time rate of heat transfer per
A : Length
B : Area
C : Volume
D : none of these
Q.no 17. In forced convection, the heat transfer depends on
A : Re, Pr
B : Re, Gr
C : mainly Gr
D : Re only
Q.no 18. Prandtl number is the ratio of
A : momentum diffusivity to mass diffusivity
B : momentum diffusivity to thermal diffusivity
C : thermal diffusivity to mass diffusivity
D : thermal diffusivity to momentum diffusivity
Q.no 19. Heat transfer by natural convection is enhanced in system with
A : high viscosity
B : high co-efficient of thermal expansion
C : low temperature gradients
D : low density change with temperature
Q.no 20. At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?
A : 0.5
B : <0.5 C : >0.6
D : <0.1
Answer for Question No 11. is c
Answer for Question No 12. is b
Answer for Question No 13. is b
Answer for Question No 14. is c
Answer for Question No 15. is a
Answer for Question No 16. is b
Answer for Question No 17. is a
Answer for Question No 18. is b
Answer for Question No 19. is b
Answer for Question No 20. is c
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