CONDUCTION, CONVECTION AND RADIATION!

YEAH, welcome back to MISS YAP'S TEACHING.

Now i'll be going through the three processes i've mentioned earlier.
CONDUCTION, CONVECTION and RADIATION!

Let's start with CONDUCTION! please turn to your textbook page 130!

What exactly is conduction?
Conduction is when heat flows through a material. Therefore, the defination of conduction is when the process of thermal energy transfer without any flow of material medium!

Well how does conduction work?
Well metals are the best conductors of heat, so let's use metals as the examples!

Metals are made up of atoms that are very closely packed together. Metals and non-metals are different as metals contain freeee electrons what will move randomly about in the atoms or molecules unlike non-metals. awww, please don't cry mr non-metals :D and yay! metals have more freedom!



So yeah, as you heat a metal, they will vibrate alot alot since they are very closely packed. As they vibrate more, they will BANG into the atoms next to them,
and then they will vibrate more again!

Then they bang again, bang bang bang into their neighbours. Metals are so inconsiderate HAH! Yeah and eventually, all these particles will be hotter than before and they will vibrate faster and faster :D

HAHAH, and then in liquids and gases, the particles are not in fixed position so this effect will NOT NOT NOT happen. That makes them UNCOOL, TEEHEE! :D

LIKE THIS!


YAY, done with conduction. Now it's time for convection. Okay, this is sooo confusing :(

So what is convection? Well, it is the transfer of thermal energy in liquids or gases but NOT in solids!

Yes gases and liquid are POOR conductors of energy and heat, and convection will work if we use this two states of matter. It will never ever ever work in solids. BUT WHY WHY WHY? Let Miss Yap do the explanation!

Okay convection only involves the movement of gasses and liquids which carry thermal energy in them.

For solids, the thermal enrgy is transferred through vibrations. When they bang into their neighbours and everybody gets upset and so they bang more and more. Convection doesn't like inconsiderate people like them :D

One example of convection is when you heat water at the bottom of the flask. It will EXPAND and grow fatter. OH NO! The expanded water will be less dense than the surrounding water and water will rise! COOOOOL YEAH!



NOW for the last process, RADIATION. oh i know you're bored, PLEASE DON'T SLEEP :D

So what is radiation? HAH, it the is energy transmitted in the form of electromagnetic waves AND high speed particles. and they DO NOT require a medium for energy transfer!

WAIT. PAUSE AND STARE. radiation has a family! does it sound familiar to you? IT IS THE ELECTROMAGNETIC WAVES!



GAMMA RAYS, X-RAYS, UV RAYS, VISBLE LIGHT, INFRARED RADIATION, MICROWAVES AND RADIOWAVES. Happy family!

Infrared radiation is absorbed and emitted by all objects and surfaces. Absorbtion of radiant heat will cause temperature to rise while emission causes temperature of the objects to decrease. So WHAT will affect the rate of infrared radiation?

WELL WELL WELL,

1. COLOURS AND TEXTURE OF SURFACES
Well, black surfaces are better absorbers of infrared radiation than shiny shite surfaces. This website http://www.newton.dep.anl.gov/askasci/phy00/phy00156.htm will explain the reason why black is a better absorber!


2. SURFACE TEMPERATURE
The higher the temperature of the surface, the higher the rate of infrared radiation!

3. SURFACE AREA
The larger the area of the object, infrared radiation will occur at a higher rate.