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Physics- Energy and Electricity
Heat energy is transferred from high to low temperature. Heat transfer takes place in
three ways:

1) Radiation is energy carried by electromagnetic waves
The sun gives out radiation in all parts of EM waves. Fortunately for us, the Earth's
atmosphere blocks most of the radiation…

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Energy Transfer
Energy exists in different forms
Energy can change from one form into another form
Energy cannot be created or destroyed

Nine types of Energy

Electrical Energy- whenever a current flows
Light energy- From the Sun, light bulbs, etc.
Sound energy- energy released by vibrating objects
Kinetic energy-is the…

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1 kilowatts is equal to 1000 watts

Power (in watts) ­ rate of transfer of energy




Example
A motor transfer 10000J of energy in 25s. What is its power?

Power = 10 000J = 400W
25s

The cost of Elctricity

Kilowatt-hours (kWh) are units of energy

A kilowatt-hour is the…

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The National Grid

The National Grid is a network of cables and transformers.


There are four main stages:
1. the fuel is burned to boil water to make
steam
2. the steam makes a turbine spin
3. the spinning turbine turns a generator
which produces electricity
4. the electricity goes…

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energy transfer diagram for the generation of electricity from a fossil fuel such as coal.

Disadvantages of using fossil fuels
Fossil fuels are non-renewable energy resources. Their supply is limited and they will
eventually run out. Fossil fuels do not renew themselves, while fuels such as wood can be
renewed…

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A wave generator is a floating
generator turning by the waves




Hydroelectricity generators are turned
by water running downhill




A tidal power station traps each high
tide and uses it to turn generators




We can convert solar energy into
electricity using solar cells or use it to
heat water directly…

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Wavelength is the distance
from one peak to the next.
Frequency is how many
complete waves. It's
measured in hertz. (1 Hz is 1
wave length). All
electromagnetic waves travel
through space at a speed of
300 million m/s. All the
different types of
electromagnetic wave travel at
the same…

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Short-wave radio signals (TV and FM radio) can, like long waves, be received at long distance
from the Transmitter. That's because they are reflected from the ionosphere ­ an
electrically charged layer in the Earth's upper atmosphere.



Microwaves

Microwaves are used for satellite communication and heating food in microwaves oven.…

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security pens
fluorescent lights


X-rays

X-rays mostly pass through skin and soft tissue, but they do not easily pass through bone
or metal. Radiographers in hospitals take X-rays photographs to help doctors diagnose
broken bones, X-rays can cause mutation which lead to cancer. Low doses cause cell
mutation and cancerous…

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Isotopes are atoms with different numbers of neutrons. E.g. The carbon-14 has two
more neutrons that `normal' carbon -12
Usually element only has one or two stable isotopes ­ like carbon -12. The other isotopes
tend to be radioactive- the nucleus is unstable, so it decays and emits radiation. Carbon-14…

Comments

Becka Sharp

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Really Useful, Thank You soooo much ^.^

Harry Hehir

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ITs not unit 1 its mostly unit 3, the notes aren't even complete

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