## Biot and Nusselt

Describe the physical significance of the Biot and the Nusselt number. (No need to write the equations.)

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__**Hint**

**Hint**

In terms of heat transfer, a small Biot number means temperature is uniform within the object and it is a lumped system.

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__**Hint 2**

**Hint 2**

The Nusselt number is a dimensionless temperature gradient at the surface.

Small Biot number means temperature is uniform within the object and it is a lumped system.

$$$Bi=\frac{thermal\: resistance\: of\: a\: solid\: to\: conduction\: heat\: transfer}{external\: thermal\: resistance\: of\: heat\: transfer}$$$

Nusselt number is a dimensionless temperature gradient at the surface.

$$$Nu=\frac{convection\: heat\: transfer}{conduction\: heat \:transfer}$$$

Small Biot number means temperature is uniform within the object and it is a lumped system.

$$$Bi=\frac{thermal\: resistance\: of\: a\: solid\: to\: conduction\: heat\: transfer}{external\: thermal\: resistance\: of\: heat\: transfer}$$$

Nusselt number is a dimensionless temperature gradient at the surface.

$$$Nu=\frac{convection\: heat\: transfer}{conduction\: heat \:transfer}$$$