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29 Dec 2025

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3 pages

Understanding Heat Transfer: Radiation, Convection, and Conduction

Katie Kozok

@katiekozok19

Heat transfer is everywhere around you - from your radiator... Show more

1 / 3

Friday 20th January

Radiation

1 all objects emit (give out) and absorb (take in) thermal
radiation (infrared radiation)

2 the hotter the

Radiation - Heat Through Waves

Every single object around you is constantly emitting and absorbing thermal radiation - yes, even you! This invisible infrared radiation is how heat travels through empty space, which is why you can feel warmth from the sun even though there's a massive vacuum between Earth and our star.

The hotter something gets, the more infrared radiation it pumps out. Think of a toaster - you can feel the heat radiating from it before you even touch it. This happens because infrared is part of the electromagnetic spectrum, travelling as waves that don't need any material to move through.

Here's a handy trick for staying cool or warm: dark, matt surfaces are brilliant at both soaking up and giving off heat radiation. That's why wearing black on a sunny day makes you sweat more. Meanwhile, light, shiny materials are rubbish at this - they reflect most radiation away, which is why emergency blankets are shiny silver.

Quick Tip: Ever wondered why car radiators are often black? It's because dark colours emit heat more effectively, helping your engine cool down faster!

Conduction - Heat Through Touch

Conduction only happens in solids and it's basically a massive game of particle pass-the-parcel. When you heat one end of a metal spoon, the particles there start vibrating more vigorously. These energetic particles bash into their neighbours, passing on their kinetic energy like a domino effect through the material.

Metals are absolutely champion conductors because they have something special - free electrons. These tiny particles can zip around freely, carrying thermal energy much faster than just particle vibrations alone. That's why a metal doorhandle feels freezing cold in winter (it's rapidly conducting heat away from your warm hand).

Materials without free electrons, like wood or plastic, are poor conductors (good insulators). The heat has to rely purely on particle vibrations, which is much slower and less efficient.

Remember: Conduction needs direct contact - no gaps allowed! Heat always flows from hot areas to cold areas, never the other way round.

Convection - Heat on the Move

Convection is heat transfer with a twist - the material itself actually moves around, creating flowing currents. When you heat particles in liquids or gases, they gain kinetic energy and spread out more, making that region less dense and causing it to rise.

Picture your radiator at home: it heats the air nearby, which expands and rises to the ceiling. As this warm air moves up, cooler, denser air rushes in from the sides to replace it. When the warm air eventually cools down at the ceiling, it becomes denser again and sinks back down. This creates a convection current - a continuous loop of moving air.

This same process explains why beaches are always windy. During the day, land heats up faster than the sea, creating rising warm air over the land. Cooler air from over the sea rushes in to replace it, creating that lovely sea breeze that makes coastal areas so pleasant.

The key thing to remember is that particles are constantly pushing and pulling each other around as they expand and contract with temperature changes.

Beach Science: The reason land heats up faster than water is because water has a much higher specific heat capacity - it takes way more energy to warm it up!

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Physics

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329

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29 Dec 2025

•

3 pages

Understanding Heat Transfer: Radiation, Convection, and Conduction

Katie Kozok

@katiekozok19

Heat transfer is everywhere around you - from your radiator warming your room to feeling the sun's warmth on your face. Understanding how thermal energy moves through radiation, conduction, and convection will help you explain loads of everyday phenomena, from... Show more

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Radiation - Heat Through Waves

Quick Tip: Ever wondered why car radiators are often black? It's because dark colours emit heat more effectively, helping your engine cool down faster!

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Conduction - Heat Through Touch

Materials without free electrons, like wood or plastic, are poor conductors (good insulators). The heat has to rely purely on particle vibrations, which is much slower and less efficient.

Remember: Conduction needs direct contact - no gaps allowed! Heat always flows from hot areas to cold areas, never the other way round.

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Convection - Heat on the Move

The key thing to remember is that particles are constantly pushing and pulling each other around as they expand and contract with temperature changes.

Beach Science: The reason land heats up faster than water is because water has a much higher specific heat capacity - it takes way more energy to warm it up!