Quiz 1

The Grashoff number is defined as the ratio of the

A.buoyancy to inertial forces.

B.buoyancy to viscous forces.

C.inertial to viscous forces.

D.buoyancy to surface tension forces

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2.  According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor)

A.2f

B.f

C.f/2

D.f/4

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3. The absorptivity of a body is equal to its emissivity

A.at a particular temperature.

B.for circular bodies.

C.under thermal equilibrium.

D.none of these.

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4. Absorptivity and refletivity of a perfect black body are respectively

A.1 and 0

B.0 and 1

C.1 and ∞

D.0 and 0.5

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5. In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)

A.α = 1; ε ≠ 1

B.α ≠ 1, ε = 1

C.α ≠ 1, ε ≠ 1

D.α = 1; ε = 1

Check Answer

1) A 2)C 3) C 4) A 5)