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The thermal boundary layer is a region where:

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  1. Heat dissipation is negligible
  2. Inertia and convection are of the same order of magnitude
  3. Convection and dissipation terms are of the same order of magnitude
  4. Convection and conduction terms are of the same order of magnitude

Answer (Detailed Solution Below)

Option 3 : Convection and dissipation terms are of the same order of magnitude
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Detailed Solution

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Concept:

The thermal boundary layer is generated as a result of molecular momentum and thermal diffusivity.

In the thermal layer, convection and dissipation are of the same magnitude.

Convection and conduction cannot be of the same magnitude as convection takes place due to the combined effect of conduction and momentum.

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