How is Heat Transferred?
#Science #Swag #Heat
Temperature can be measured in Degrees Celsius (°C).
Heat is a form of energy and is measured in joules (j). Another name for heat energy is Thermal energy. The amount of heat energy in an object depends on its temperature, mass and material.
The sparks are at a high temperature but they don't have enough thermal energy to burn the hand.
The red liquid expands as the temperature rises.
Hot substances emit infrared radiation which can be absorbed or reflected. All shiny materials reflect the most infrared radiation.
Thermal imagers also use radiation. They convert infrared radiation into temperature maps. This can be used to see things during the night, film hot parts of the Earth from space or show the temperatures in the human body.
Thermal imagers can also forecast the weather by taking pictures of clouds.
Metals are good thermal conductors and wood and platic are good thermal insulators.
When the particles in a solid start to vibrate, they start to gain more space and this causes the solid to expand. When the particles lose the thermal energy, the particles come back into place and the solid returns to its origianl form.
When a solid expands, its mass stays the same altough it takes up more space decreasing its density.
When a fluid is heated, the particles move around and it becomes less dense. if only one part of the fluid is being heated, that part starts to rise becuase it is less dense than the other part. Coolder fluid comes in and takes its place. This is how a convection current is formed.
Convection currents also take place when a substance is colder than the air around it as showed in this diagram:
It is possible to change a gas back into a liquid. This process is called condesation. When cooling a liquid, it will change into a soid at its freezing point. The freezing point and melting point of a substance are always the same.
When the human body is hot, it sweats to help you cool down. The skin produces the sweat and it absorbs the heat as it evaporates. This is why many sports clothes 'wick' sweat. This means it spreads the sweat so it can evaporate quicker.