Firewalking

This is good to know, but please do not try this yourself!



Read more about it here: How can you walk across hot coals?

Molecules in Motion

Sing along!

Where is the wave?

If you've written a song or made an MTV on a physics topic and uploaded it somewhere on the WWW, please share the link with me so I can feature it in my blog here. Thanks!

For your viewing/singing pleasure

Lyrics:
The electromagnetic spectrum
Is just a name
Of a range of radiation
Let me tell you what they are

Radio waves
Microwaves
Infra-red radiation
Visible light
Ultra-violet
X-rays
Gamma rays

From the TV station to your living room
That is the work of radio waves
Heating food in just seconds
Microwaves do that

Heat treatment for illness
Take pictures in the dark
They are even in your remote control
Infra-red radiation

(repeat)

Red Orange Yellow Green Blue
Indigo Violet
That is the only part of the spectrum
That can be seen by us

The suntan on your skin
Kill bacteria and viruses
Use to detect forgery
That is ultra-violet

(repeat)

See your broken bones and the hidden bombs
That is the work of x-rays
Kill cancer cells and sterilize
Dangerous gamma rays do that

Now we have completed
The electromagnetic spectrum
If you still do not understand
Then play this song again!

(repeat)

Let's try this out with the Karaoke Version~!

Cooling fins & heat sinks

Heat sinks function by efficiently transferring thermal energy ("heat") from an object at a relatively high temperature to a second object at a lower temperature with a much greater heat capacity. This rapid transfer of thermal energy quickly brings the first object into thermal equilibrium with the second, lowering the temperature of the first object, fulfilling the heat sink's role as a cooling device. Efficient function of a heat sink relies on rapid transfer of thermal energy from the first object to the heat sink, and the heat sink to the second object.

Mdm Koo:
Therefore, a good conductor is being used for rapid transfer of thermal energy.

The most common design of a heat sink is a metal device with many fins. The high thermal conductivity of the metal combined with its large surface area due to the fins results in the rapid transfer of thermal energy to the surrounding, cooler material. This cools the heat sink and whatever it is in direct thermal contact with. Use of fluids (for example coolants in refrigeration) and thermal interface material (in cooling electronic devices) ensures good transfer of thermal energy to the heat sink. Similarly a fan may improve the transfer of thermal energy from the heat sink to the air by moving cooler air between the fins.

Mdm Koo:
Many thin metal fins with gaps in between
-> large surface area in contact with surrounding cooler air
-> rapid transfer of thermal energy away from source to surrounding

SOURCE - http://en.wikipedia.org/wiki/Heat_sink



To overcome the problem of overheating, conduction, convection and radiation are used to remove as much heat as possible from the device to keep it cool.

Conduction - the cooling fins are made from a good conductor and fastened firmly to the engine/chip. This allows thermal energy to be conducted effectively from the engine/chip to the cooling fins.

Convection - the surface area of the metal in contact with air is increased by shaping the cooling fins into many flat layers. Once the thermal energy is conducted to the air, convection will bring the thermal energy away. In the case of a microprocessor chip, fan is usually mounted to increase the rate of convection.

Radiation - the increased surface area of the cooling fins increases the rate of energy transfer by radiation.