Project ForgeHeat Transfer
Convection & Radiation
GATE 2012
Easy
For an opaque surface, the absorptivity (α), transmissivity (τ) and reflectivity (ρ) are related by the equation:
- Aα+ρ=τ
- Bρ+α+τ=0
- α+ρ=1
- Dα+ρ=0
Explanation
In general, α+ρ+τ=1 (energy balance for incident radiation). An opaque surface transmits nothing, so τ=0, leaving α+ρ=1.
Source: GATE ME 2012 (Booklet Code A) (2012)
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