Physics- P1

P1.1

Kinetic Theorey

• Solid melts into Liquid
• Liquid evaporates into Gas
• Gas condenses into Liquid
• Liquid freezes to a Solid
• Solid sublimition into Gas
• Gas dispositions into Solid

Surfaces and Radiation

• All surfaces can emit and absorb thermal radiation.
• Shiny Surfaces- A large amounyt of infrared radiation is reflected. Therefore, shiny surfaces are bad absorbers and emitters of thermal radiation, but good reflecters.
• Matt Surfaces- Very little infrared radiation is reflected from the surface. Therefore, matt surfaces are good aborbers abd emitters of infrared radiation but are bad reflecters.

Conduction

• Conduction mainly occurs in Solids.
• Liquids and gases are not as good conductors as their particles arn't as closely packed together.
• In a solid, when heat travels by conduction, the particles near heat source start to vibrate.
• These vibrations are then passed along to the next atom and so on through the material.
• Metals are good conductors as they contain free electrons. The outer electrons of a metal atom are held together losely by the positively charged nucleus and so are able to break away and move freely amongst the now positive ions. These free electrons move around randomly.#
• When a metal is heated the free electrons gain more kinetic energy and diffuse and collide more often with other free electrons and ions in coolerparts of the metal which results in energy being transferred.
• in a non- metalic all the electrons are held tightly to the nucleus so enery transfer only takes place by the atoms/ molecules vibrating more nad passing on the energy. This is much less effective than energy transfer by free electrons. This is why metals are…