Test: Heat Transfer - JAMB MCQ

Conduction refers to the transfer of heat through a material by direct contact of particles. When heat is applied to one end of a material, the particles at that end gain energy and start vibrating. These vibrating particles collide with neighboring particles, transferring the heat energy from one particle to another.

Radiation is the transfer of heat energy through electromagnetic waves. Unlike conduction and convection, radiation does not require a medium for heat transfer. Examples of radiation include feeling the warmth of the sun on your face or the heat emitted by a fire.

The temperature gradient is the change in temperature per unit length across a material. It represents the rate at which the temperature changes along a specific direction. A steeper temperature gradient indicates a more rapid change in temperature over a given distance.

Thermal conductivity is the property of a material that determines its ability to conduct heat. It represents how well a material can transfer heat through conduction. Materials with higher thermal conductivity can transfer heat more efficiently than materials with lower thermal conductivity.

Heat flux refers to the rate of heat transfer per unit area. It represents the amount of heat energy transferred through a given area per unit time. Heat flux is influenced by factors such as the temperature difference and thermal conductivity.

Aluminum has higher thermal conductivity compared to wood, glass, and rubber. It is an excellent conductor of heat and is widely used in various applications where efficient heat transfer is required, such as in heat sinks and cooking utensils.

Air has a low thermal conductivity compared to copper, steel, and silver. It is considered an insulator when it comes to heat transfer. Air-filled gaps or spaces are often used as insulation materials to reduce heat transfer through conduction or convection.

The energy radiated or absorbed by a surface depends primarily on its temperature. According to Stefan-Boltzmann's law, the rate of radiation emitted by a surface is proportional to the fourth power of its absolute temperature. The higher the temperature, the greater the energy radiated by the surface.

A black surface is a good absorber and emitter of radiation because it absorbs most of the radiation incident on it. Black surfaces are designed to absorb a wide range of wavelengths of electromagnetic radiation, converting them into heat energy. Due to its high absorbance, a black surface can also emit a significant amount of radiation.