Factors Influencing Thermal Radiation Emission

Steps:

• The rate of thermal radiation emission follows the Stefan-Boltzmann law: power P = ε σ A T^4.
• Surface temperature (T) directly affects emission, as P is proportional to T^4.
• Surface area (A) directly affects emission, as P is proportional to A.
• Surface colour influences emissivity (ε), with darker colours having higher ε, increasing emission.

Why A is correct:

• Stefan-Boltzmann law confirms all three factors—temperature (T^4), area (A), and colour (via ε)—determine radiation rate.

Why the others are wrong:

• B omits colour, ignoring its effect on emissivity.
• C omits area, despite direct proportionality in the formula.
• D omits temperature, the dominant factor via T^4.

Final answer: A