Physics-Energy transfer by heating

Infrared radiation

• Infrared radiation is energy transfer by electromagnetic
• All objects emit infrared radiation
• The hotter an object is the more infrared radiation it emits in a given time

Surface and radiation 

• Dark, matt surfaces emit infrared radiation more quickly than light, shiny surfaces
• Dark, matt surfaces absorb infrared radiation more quickly than light, shiny surfaces
• Light shiny surfaces reflect more infrared radiation than dark, matt surfaces

States of matter

• Flow, shape, volume and density are the properties used to describe each state of matter
• The particles in a solid are held next to each other, vibrating in their fixed positions
• The particles in a liquid move about at random and are in contact with each other
• The particels in a gas move about randomly and are mich farther apart than particles in a solid or liquid

Conduction 

• Metals are the best conductors
• Materials such as wool, and fibreglass are good insulators
• Conduction in a metal is mainly due to free electrons transferring energy inside  the metal 
• Non-metal are conductors because they do not contain fee electrons
• Poor conductors are called insulators

Convection

• Convection is the circulation of a fluid (liquid or gas) caused by heating it
• Convection takes place only in liquids and gases (fluids)
• Heating a liquid or a gas makes it less dense so it rises and causes circulation 

Evaporation and condensation

• Evaporation is when a liquid turns into a gas
• Condensation is when a gas turns into a liquid
• The rate of evaporation is increased by:
• Increasing the surface area of the liquid
• Increasing the temperature of the liquid
• Creating a draught of air across the liquid's surface
• The rate of condensation is increades by:
• Increasing the surface area
• Reducing the surface temperature

Energy transfer by design

• The rate if energy transfer to or from an object depends on:
• The shape, size and type of materials of the object 
• The materials the object is in contact with
• The temperature difference between the object and its surroundings

Specific heat capacity

• The greater the mass of an object, the more slowly its temperature increases when it is heated
• The rate of temperature change in a substance when heated depends on the energy transferred to it, its mass and its specific heat capacity
• The equation for specific heat capacity is: E=m x c x o
• Where:
• E is energy transferred, J
• m is mass, kg
• c is specific heat capacity, J/kg degrees
• o is temperature change, degrees

Heating and insulating bulidings

• The rate of energy transfer to or from our homes can be reduced
• U-values tell us how much energy per second passes throguh different materials. The lower the U-value the better the material is as an insulator
• Solor heating panels do not use fuel to heat water but they are expensive to buy and install