Energy Transfer by Heating
Conduction is like a relay race where energy passes from particle to particle through materials. Metals are brilliant at this because their electrons can move freely, which is why that metal spoon heats up so quickly in your tea!
Different materials have different thermal conductivity - basically how good they are at passing heat along. Copper beats steel, steel beats glass, and glass beats wood. The greater the thermal conductivity, the faster energy transfers through the material.
Good insulators work by having low thermal conductivity - they're rubbish at passing heat along, which is exactly what you want! Think about those foam cups that keep your coffee warm. The energy transfer through any material depends on three things: the temperature difference, how thick the material is, and its thermal conductivity.
Key Point: All objects constantly emit and absorb infrared radiation - even you! This is why thermal imaging cameras can see you in the dark.
Everything around you is glowing with invisible heat radiation. Earth's temperature depends on this balance between absorbing infrared from the sun and radiating heat back into space. When you feel warmth from a radiator across the room, that's infrared radiation reaching you.
Insulating buildings is all about slowing down heat transfer. Houses lose energy through conduction, convection, and radiation, so builders use loft insulation, double glazing, cavity wall insulation, aluminium foil, and thicker bricks to keep your heating bills down and your home cosy.