Q:   Biot number is defined as

• A:  k/hL
• B:  kL/h
• C:  hL/k
• D:  h/kL

Q:   With rise in temperature, thermal conductivity of solid metals ...

• A:  Increases
• B:  Decreases
• C:  Remain same
• D:  First increases then decreases

Q:    The steady state heat conduction equation in radial direction in spherical coordinates in absence of any heat source is given by ...

Q:   The dimensionless time, called fourier number, is defined as ...

• A:  ( α τ ) / L²
• B:  L² / ( α τ )
• C:  ( α τ ) / L
• D:  L²τ/ α

Q:    It is desired to increase heat dissipation rate from the surface of an electronic device of spherical shape of 5mm radius exposed to convection h= 10 W/m²K by encasing it in a spherical sheath of conductivity k= 0.04 W/m²K. For maximum heat flow, the diameter of the sheath should be ...

• A:  12mm
• B:  18mm
• C:  16mm
• D:  8mm

Q:   Heisler's chart shows the temperature time history of a solid in transient heat conduction as a function of ...

• A:  Fourier & Biot number
• B:  Reciprocal of Fourier number & Biot number
• C:  Fourier number & reciprocal of Biot number
• D:  Reciprocal of Fourier number & reciprocal of Biot number

Q:   The maximum temperature at the centre of solid sphere of radius R having heat generation of q_G(W/m³) is given by ...

Q:   The temperature profile for heat conduction through a wall of constant thermal conductivity in the presence of a heat source is ...

• A:  a straight line
• B:  parabolic
• C:  logarithmic
• D:  hyperbolic

Q:   In one-dimensional transient numerical method, the choice of the time interval Δt in the finite difference equations is limited by the condition that Δx²/αΔt

• A:  is less than 2
• B:  is euqal to 2
• C:  is greater than 2
• D:  either b or c

Q:   The quantity having the dimesion of time is often called the time constant of a thermo-couple

• A:  hA/ρCV
• B:  hV/ρCA
• C:  ρCV/hA
• D:  ρCA/hV