What is the primary mechanism by which thermal radiation transfers energy?

Explanation:

Thermal Radiation and Its Mechanism

• Thermal radiation is a mode of heat transfer that occurs through the emission of electromagnetic waves, primarily in the infrared spectrum, but it can also include visible light and other wavelengths. This form of energy transfer does not require a medium, meaning it can occur in a vacuum. The energy is emitted by all bodies that have a temperature above absolute zero, due to the thermal vibrations of their molecules and atoms. The amount and nature of the radiation depend on the temperature and the surface properties of the body.

Radiation as a heat transfer mechanism is governed by Stefan-Boltzmann’s law, which states:

Q = σ × A × T⁴

Where:

• Q = Heat transfer via radiation (W)
• σ = Stefan-Boltzmann constant (5.67 × 10⁻⁸ W/m²K⁴)
• A = Surface area of the body (m²)
• T = Absolute temperature of the body (K)

Thermal radiation is characterized by the following:

• Electromagnetic Waves: It is the primary mechanism by which thermal radiation occurs. These waves can travel through a vacuum, making radiation the dominant form of heat transfer in outer space.
• Emissivity: The ability of a material to emit energy as thermal radiation is determined by its emissivity, which ranges from 0 (perfect reflector) to 1 (perfect emitter or blackbody).
• Temperature Dependence: The intensity and wavelength distribution of the emitted radiation depend on the temperature of the object.