Question

Radiation heat transfer in the system is characterized by

• A. Due to bulk fluid motion, there is a transport of energy
• B. Thermal energy transfer as vibrational energy in lattice structure of the material
• C. There is circulation of fluid by buoyancy effects
• D. Movement of discrete packets of energy as electromagnetic waves

Hint:

Remember the distinct mechanisms for each mode of heat transfer: - \textbf{Conduction}: Vibration of particles (solids, liquids, gases). - \textbf{Convection}: Bulk motion of fluid (liquids, gases). - \textbf{Radiation}: Electromagnetic waves (no medium required).

Answer 1

The Correct Option is D

Step 1: Understand the modes of heat transfer.
Heat transfer can occur by three primary modes: conduction, convection, and radiation.
Conduction: This involves the transfer of heat through direct physical contact, typically in solids, due to vibration and movement of atoms and molecules.
Convection: This is the transfer of heat through the movement of fluids (liquids or gases), involving the bulk motion of the fluid carrying thermal energy.
Radiation: This mode involves the transfer of heat through electromagnetic waves, which does not require a medium.
Step 2: Analyze the characteristics of radiation heat transfer.
Radiation heat transfer is distinct from conduction and convection because it does not require a material medium for energy propagation. Instead, energy is transmitted in the form of electromagnetic waves, which are emitted by matter due to the thermal motion of its constituent particles. These electromagnetic waves carry discrete packets of energy called photons. When these photons are absorbed by another body, their energy is converted into thermal energy, thus transferring heat.
Step 3: Evaluate the given options.
(1) "Due to bulk fluid motion, there is a transport of energy": This describes convection heat transfer.
(2) "Thermal energy transfer as vibrational energy in lattice structure of the material": This describes conduction heat transfer in solids.
(3) "There is circulation of fluid by buoyancy effects": This describes natural convection, a specific type of convection.
(4) "Movement of discrete packets of energy as electromagnetic waves": This accurately describes radiation heat transfer. Energy is transported by photons (discrete packets) which are electromagnetic waves. Therefore, radiation heat transfer is characterized by the movement of discrete packets of energy as electromagnetic waves. The final answer is \( \boxed{\text{4}} \).