Thermal Energy Transfer Flashcards

Flashcards about thermal energy transfer for exam review.

Temperature

Refers to how cold or hot an object is.

Heat

The amount of thermal energy transferred from a hot region to a colder region.

SI unit of temperature

Kelvin (K)

Expansion

Particles gain energy and vibrate more vigorously, increasing the distance between particles, leading to increased volume and decreased density.

Contraction

Particles lose energy and vibrate less vigorously, decreasing the distance between particles, leading to decreased volume and increased density.

Why do gases expand and contract more than liquids and solids?

Gases have the weakest forces of attraction between particles, allowing them to move much further apart compared to liquids and solids.

What is a bimetallic strip?

A strip used in thermostats and bimetallic thermometers that utilizes the different expansion rates of two metals.

During expansion, how will a bimetallic strip bend if it is made of brass and steel (where brass expands more)?

The bimetallic strip will bend downwards with brass on the outward side and steel on the inward side.

What is conduction?

Transfer of heat energy without the physical movement of the medium.

How does heat transfer occur through conduction?

Particles near the heat source gain thermal energy and vibrate more quickly, colliding with neighboring particles to transfer energy.

Why is gas a less effective conductor of heat?

The particles are far apart, hindering effective energy transfer through collisions.

Why are metals better conductors of heat?

They have delocalized electrons that can move easily and quickly to transfer thermal energy.

What is convection?

Transfer of thermal energy by the physical movement of a fluid (liquid or gas) due to density differences.

How does convection work?

Heated fluid expands, becomes less dense, and rises, while cooler, denser fluid sinks to take its place, creating convection currents.

What is radiation?

Transfer of thermal energy without the need for a medium.

What type of radiation do all bodies and objects emit?

All objects emit infrared radiation, and the rate of emission increases with temperature.

What factors affect the rate of thermal energy transfer by radiation?

The higher the surface temperature, the larger the surface area, and the type of surface (dull, rough, and black surfaces are better emitters/absorbers).

What is the purpose of the vacuum in a vacuum flask?

Prevents heat loss by conduction and convection, as these cannot occur in a vacuum.