Physics P1 - created from Mind Map

Seite 1

Transferring energy

Energy efficiency

Electricity

Waves

The Universe

Colours

Methods

U-Values

Specific Heat Capacity

Dark/Matt - Good radiation emitter and absorber

Light/Shiny - Bad radiation emitter and absorber

Conduction - When particles in a solid vibrate and collide

Convection - When particles in al liguid or gas are given more energy, they spread out so the hot material rises

Radiation - All particles emit infra-red radiation

Evaporation - When a liquid gains more energy and escapes as a gas (Increased by temperatur, surface area and wind)

Condensation - When a gas loses energy it returns to a liquid

They tell us how much heat passes through a material. Lower=Less heat

Energy loss(J) = U-value(W/M^2/°C) x Area(M^2) x Temperature difference(°C)

How much energy is require to raise the temperature of an object by 1°C

Energy(J) = Mass(Kg) x SHC(J/Kg°C) x Temperature change(°C)

Energy cannot be created or destroyed only transferred.

We use sankey diagrams to represent energy efficiency

Cost

Generating Electrcity

The national grid

We need to know the energy transferred in a given time

We also need to know kilowatt-hours

1 Watt = 1 Joule/Second

Energy transferred(J) = Power(W) x Time(S)

Energy transferred(KWH) = Power(KW) x Time(H)

Non-Renewable

Renewable

Fossil fuels (Coal, oil, gas)

Nuclear fission (The splitting of atoms)

Wind - Turbines drive generators. Many are required and the wind is unreliable but the turbines require very little maintenance

Hydroelectric - Falling water from rivers or reservoirs turn turbines. it is reliable but dams are expensive to construct

Tidal - Seawater is trapped at high tide and then at low tide it is released which drives turbines. It is reliable but barrages are expensive to construct

Waves - The rise/fall of waves drives turbines but it is unpredictable and very rarely used

Geothermal - Water is superheated underground into steam which on the surface drives turbines. It is reliable but there are limited areas of use e.g. Iceland

Solar cell - They turn sunlight into energy. They are expensive and only convert 20% of the Sun's energy. They only work when the sun is visisble

When energy travels along a wire some disspates. Increasing the voltage reduces the energy lost. Transformers are use to in crease/decrease the voltage

Types

Electromagnetic

Reflection - When a wave bounces off an interface between two materials. The wave changes direction but doesn't cross the interface

Refraction - When a wave crosses an interface between two materials. The wave changes direction unless the rays hit the interface at right angles

Diffraction - When waves pass through a gap or over an obstacle that is similar in size to the wavelength of the wave. The wave spreads out through the gap

Mirrors

Transverse - The oscillations are at aright angle to the direction of travel and energy transfer

Longitudinal - The oscillations are in the same direction as the travel and energy transfer

All these transverse waves travel at the same speed in a vacuum and form a continuous spectrum

The angle of incidence is equal to the angle of reflection

Doppler Effect

Expanding

If a source is moving towards us we hear a high-pitched sound

If the source is moving away from us we hear a low-pitched sound

Because Waves in front of a source become squashed so frequency increases and wavelength decreases

Because waves behind a source become stretched so frequency decreases and wavelength increases

Red-Shift

Cosmic Microwave Background Radiation (CMBR)

When objects have longer wavelengths they move to the red end of the electromagnetic spectrum so therefore if we see more red the object is moving away from us

This used as evidence as for the big bang (expansion from a single point)

Is found throughout the universe and shows how the wavelengths have increased over time