# EDEXCEL GCSE COMPLETE FIRST YEAR PHYSICS.

everything you need to get an a* on your year 10 or year 9 if your on excelerated ciriclum exams. hope this helps

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• Created by: Annarose
• Created on: 10-06-12 16:56

## CONVERSION OF ENERGY

Energy can be converted easiy, ie at a fair, on a rollercoaster when you go up you are gathering potentail energy, the further from the ground you become the come the more potential energy you would have. As the carriage goes down the hill the potential energy is converted into kineasthetic energy. This is the energy of movement.

Also at a fair if you were to eat candy floss you would be transfering food energy too energy for your body. Other energy transformations include if someone hit someone else, energy from your body would be transformed into heat energy.

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## EFFICIENCY CALCULATIONS

To calculate efficency you have to use the calculation:

useful energy transferred by the device

efficiency=    --------------------------------------------------------

-------------------total energy supplied to the device

--------------------

-----------------------x100%

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## ABSORBERS & EMITTERS (COLOUR)

black matt surfaces are the best at absorbing and emitting infared but they are also the worst because they are also good conductors as they remain neutral.

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## PROPERTIES OF P AND S WAVES

P waves move in circles but they travel in an intergrating line. So it moves backwards and forwards much like ac current. P waves are longitudal.P waves travel faster than S waves. S waves move from side to side as they pass. These are called transverse waves.

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## USE OF SPEED = DISTANCE/ TIME

When you are trying to find out how fast a wave is (seismic/ radiation) is traveling you use the formula:

------------------------------    -distance

-----------------speed= --------------------------

-------------------------------      time

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## PREDICTING EARTHQUAKES

Scientists preidct when earthquakes are likely to happen by monitering small jerks in the tectonic plates. But this technique cannot give an accurate day or time of when there will be an earthquake, all they can say is when and where an earthquake is likely to be. It is currently impossible to predict more accurately when earthquakes will be.

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## SOLAR POWER

solar power is generated when sun hits the surface of the solar pannel, this heat is used to heat the air under the glass. The hot air raises up the tower moving turbines as it moves, genertaing electricity.

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## A.C AND D.C CURRENT

ALTERNATING CURRENT-

This means it flows by changing direction of the flow many times per second this reduces friction by discharging the flow. This means that the current can be transported further.

DIRECT CURRENT-

This means the current flows continuously this means friction is higher so the current cannot flow far.

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## TRANSFORMERS

There are two types of transformers:

A) step up- where the voltage of the flow is increased, eg to help energy to not be wasted while being transported on powerlines.

B) step down- where the voltage is decreased eg to be used in homes and shops.

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- Solar energy is a completely renewable resource. This means that we will always have this resource, it will never run out, unlike fossil fuels.

- They are quiet.

- They do not give out pollution while they make energy.

- Very little maintenance is required to keep sola pannels working.

- Saves money.

- They are easily to install.

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## CALCULATING PAYBACK TIME

To calculate payback time you do money saved per year - money spent installing yu should be left wuht a negative number. You keep adding money saved per yearonto this until you no longer have a negative number.

such as:

if solar panels were 1000 pounds, and you saved 200 pounds a year, it would take 5 years to get your payback.

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## REFRACTON

The change of speed and direction a wave when it enters a new material with a different density, causing the wave to bend.

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## USE OF WAVESPEED = FREQUENCY X WAVELENGTH

v= f x l

Also means:

wavespeed = frequency x wavelength

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## DIFFERENCES BETWEEN TRANSVERSE AND LONGITUDAL WAVE

Transverse waves are S seismic waves.

Longitudal waves are P seismic waves.

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## PROPERTIES OF XRAYS

xrays are the second most dangerous and most powerful type of wave in the electromagnetic spectrum it is used to look at the bones in humans and animals

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## DANGERS OF X RAYS AND INFARED

Infared can burn your skin, such as infared from the sun can cause sunburn.

The dangers of x rays include:

-cancer of the bone marrow
-leukemia
-cancer
-skin burns
-reduction of blood supply
-damaged and mutated cells.

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## POSITIONING THE TELESCOPES

To get the best results you should put telescopes in unlightpolluted/ unihabited areas as you will get a clearer view of space.

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## RED SHIFT

Waves emmitted by something moving away from the observer have their wavelength increaed and frequency decreased compared to waves from a stationary object.

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## EVIDENCE SUPPORTING THE BIG BANG THEORY

- The universe is expanding. This could haveben caused by the big bang and if it ere it is proven that th expasion would still hapening as part of the aftermath of the big bang.

- The universe is redshifting. This isquite possibly as result of the bg bang.

- Radiation called comic microwave background (cmb) radiation. This would han released at the begining of the universe.

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