This type of surface is a good absorber and emitter of thermal radiation
Dark, rough (matt) surface
This type of surface is a bad absorber and
... [Show More] emitter of thermal radiation
Light, shiny surface
In this process particles vibrate colliding with each other passing energy along. Solids are best at it, then liquids, then gases.
Conduction
In this process particles move around carrying energy with them. Gases are best at it, then liquids then solids
Convection
This process doesn't require a medium (substance) to transfer energy. The energy is carried in the form of waves
Radiation
Factors affecting the rate of heat transfer
1. Temperature difference to the surroundings
2. Surface area
3. Nature of surface (e.g shiny/matt)
The total energy supplied to a device or an appliance. It is often electrical
Total Input Energy
Energy converted by a device into the form(s) the device was designed for.
Useful energy
Energy converted by a device into the form(s) the device was NOT designed for.
Wasted energy
Useful energy transferred by the device divided by total energy input to the device
Efficiency
Energy cannot be created or destroyed only transformed into other forms
The principle of conservation of energy
Where does all energy end up eventually?
It is transferred to the surroundings, warming them in the process.
The unit of energy used in electricity bills
kilowatt-hour (kWh)
What are the useful and wasted energies transformed by a radio?
USEFUL: Sound
WASTED: Heat
What are the useful and wasted energies transformed by a TV?
USEFUL: Sound, Light
WASTED: Heat
What are the useful and wasted energies transformed by a hairdryer?
USEFUL: Heat, Kinetic
WASTED: Sound
What are the useful and wasted energies transformed by a car?
USEFUL: Kinetic
WASTED: Heat, Sound
The unit of energy normally used (expect in electricity bills)
joules (J)
Absorption
When a wave hits an object and is absorbed the energy of the wave can heat up the object
Reflection
When a wave 'bounces off' an object
Transmission
When a wave travels through a material (e.g. visible light through glass)
What are the three types of nuclear radiation in order from most to least penetrating?
Gamma, Beta, Alpha
What are the three types of nuclear radiation in order from most to least ionising (damaging)?
Alpha, Beta, Gamma
Advantages of Digital over Analogue
Digital signals are affected less by interference and can be easily processed by computers.
What is an alpha particle?
A helium NUCLEUS.
What is a beta particle?
An electron.
Which types of nuclear radiation are deflected by electric and magnetic fields
Alpha and Beta (they are always deflected the opposite way to each other)
Which particles are found in the small central nucleus of the atom?
Protons and Neutrons
What is a radioactive substance
A substance that gives out radiation from the nuclei of its atoms (no chemical or physical change can stop this happening)
Half-life
The time it takes for the number of radioactive nuclei in a sample to halve. (or the time it takes for the count rate from a radioactive source to halve).
Advantages of Space-based (orbital) telescopes
No atmospheric distortion. Can see parts of the spectrum which are absorbed by the atmosphere (UV and X-ray)
Disadvantages of Space-based (orbital) telescopes
Very expensive to launch and maintain.
Advantages of ground based (terrestrial) telescopes
Relatively Cheap. Easy to access for repairs and upgrades.
Disadvantages of ground based (terrestrial) telescopes
Suffer from atmospheric distortion. Can't look at all parts of the EM spectrum (esp. UV and X-ray)
What is red shift?
The light from distant galaxies appears shifted to the red end of the spectrum suggesting they are moving away from us.
The Big Bang Theory
The best current theory for how the Universe began, with a giant 'explosion' that created all matter, energy and even space and time itself.
Atoms of an element always have the same number of _______ in the nucleus.
protons (e.g. all Carbon atoms have 6 protons)
Atoms of different isotopes of an element will have different number of _________ in the nucleus.
neutrons (e.g. carbon-12 has 6 neutrons, carbon-14 has 8 neutrons). Both have 6 protons.
Uses of Alpha Radiation
Smoke alarms ( A long half-life source should be used to avoid having to replace it)
Dangers of Alpha Radiation
An alpha source is very dangerous when swallowed or inhaled as alpha particles cannot normally penetrate the skin.
Uses of Beta Radiation
Thickness control for paper mills, aluminium foil. ( A long half-life source should be used to avoid having to replace it)
Dangers of Beta Radiation
Beta sources are dangerous outside the body as beta radiation can penetrate into internal organs.
Turbine
Part of a power station where high pressure steam rotates the turbine blades
Furnace
The place where fuel is burned in a fossil fuel power station. The energy released is used to heat water in a boiler.
Generator
Connected to the turbine. It contains a magnet and wire coils which transform the kinetic into electrical energy [Show Less]