Physics 1

Physics 1

1. Heat and temperature

   • Energy is transferred from a hotter Body to a colder one
   • Temperature can be represented by a range of colours in a thermogram : hot by red/white/ yellow; cold by black / dark blue/ purple
   • Energy is transferred when a substance changes temperature. The amount of energy transferred depends on the mass , temperature change and specific heat capacity
   • Energy transferred= mass x specific heat capacity x temperature change
   • Energy transferred= mass x specific latent heat

2. Energy transfer

   • Air is a good insulator and reduces energy transfer by conduction. Conduction in a solid is by the transfer of kinetic energy.
   • Trapped air reduces energy transfer by convection are caused by density changes.
   • Shines surfaces reflect infrared radiation to reduce energy trasfer.
   • You can save energy by: double glazing, loft insulation, curtains, cavity wall insulation.
   • Efficiency = useful output energy x100 / total energy input

3. Waves transfer energy

   • warm and hot objects emit infared radiation (used for coking)
   • all waves have amplitude, frequency and wavelength e.g. wave speed+ frequency x wavelength
   • laser light, visible and infared are used to send signals along optical fibres by total internal reflection.
   • An electromagnetic waves can be reflected, refracted and diffracted.
   • radio waves, microwaves, in fared, visible light and ultraviolet are some of the waves in the electromagnet spectrum

4. The sable earth

   • earthquakes waves travel through the earth
   • longitudinal P waves travel faster than transverse S waves.
   • CFCs are causing the ozone layer to become thiner.