Convection | MCQs

Explanation

A thermos flask is designed to reduce heat transfer through all three methods:

• Conduction: The flask has a vacuum insulation, which eliminates conduction through the container.
• Convection: The flask's design and vacuum insulation prevent convective heat transfer.
• Radiation: The flask's reflective coating minimizes radiant heat transfer.

Explanation

The cooling fins at the back of a refrigerator are typically made of a black, rough surface to maximize heat radiation. This design:

• Increases the surface area for heat transfer
• Absorbs heat from the surrounding air
• Emits heat more efficiently due to the rough surface

Explanation

• Heat is a form of energy associated with the motion of molecules in a substance.
• As molecules vibrate, rotate, and collide, they transfer energy from one another, resulting in the sensation of heat.

Explanation

• Convection is the primary mode of heat transfer in liquids and gases, where heat is transferred through the motion of fluids.
• This motion creates circulation currents that carry heat energy from one location to another.

Explanation

• Convection is the mode of heat transfer that occurs when a fluid (such as a gas or liquid) moves and carries heat energy from one location to another.
• This transfer of heat occurs due to the bulk motion of the fluid.

Explanation

• Conduction is the transfer of internal energy (heat) through direct contact between particles or molecules.
• Including collisions and movements of electrons within a substance.
• This process occurs in solids.