Some people still argue that there is no such thing called â€˜hotâ€™ or â€˜coldâ€™. Cold or hot is merely a sensory experience and if one thinks in physical terms, cold is not a thing but the absence of heat!
What is Heat Transfer?
Letâ€™s take an example. You put an ice cube in your coffee for cooling it, but if seen form the point of view of physics, the description is usually backwards! What takes place is heat flows from coffee to ice to raise its temperature enough to melt it and the latent heat absorbed in the process cools down your coffee.
Heat transfer is the flow of heat from one substance to another due to the prevailing difference between both the substances. Students should have a clear concept about these basic concepts of physics. One can take Heat Transfer Assignment Help for guidance.
Heat and temperature are different!
Then there is confusion between temperature and heat. While both sound synonymous, they are not so much so. Technically speaking, temperature is average motion of all the atoms and molecules present in a body; while heat is the energy which flows as a result of temperature differences.
Heat is always transferred from hotter to cooler objects. Heat Transfer Homework Help shall guide you in a simpler way.
Conduction, convection and radiation!
Heat is transferred only by these three methods, namely conduction, convection and radiation.
Conduction takes place in solids (especially metals). This is because molecules are densely packed and molecular collisions lead to transfer of heat. Metals consists of more free electrons, thus it is better conductor of heat.
If you think of a queue of people standing shoulder to shoulder and passing a â€˜whisperâ€™ down line; then in this case this â€˜whisperâ€™ would be kinetic thermal energy. Of course some secret in the whisper shall be garbled due to time. Thus some energy would be lost in conduction.Â Take help from Heat Transfer Assignment Help for finishing various assignments given by school teachers.
Convection is a way to transfer heat in fluids. In physics the term â€˜fluidsâ€™ refers to both liquids and gases. Different from conduction, in case of convection it involves the entire movement of heated materials. If air is heated, it shall flow to displace cold air in its path and set up convection current.
Think of an oven (forced convection current), convection currents by the sea side where warm air replaces cold air and vice versa or working of a refrigerator.
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Have you ever wondered, if sun rays are so powerful causing severe bums due to long exposures, then how can the upper atmosphere be so cold? Isnâ€™t the Sun closer to the outer space or upper atmosphere?
The probable answer is there is absence of any medium in the outer space for carrying convectional currents and even in upper atmosphere, the air molecules are so far apart that there is hardly any defined medium.
You must be again wondering, then how come we feel the heat?
It is by radiation which is radically different from other two methods of heat transfer. Radiation involved electromagnetic energy whereas conduction and convection involves thermal kinetic energy.
The sunrays, x-rays, microwaves, radio waves, visible rays and gamma rays travel through electromagnetic spectrum or radiation.
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The world would be a dead planet without heat transfer techniques. Please go through, â€˜Four useful real life examples which explains momentum easily!â€™ for detailed information about momentum and real life applications.