Download P2 – Living for the future

P2 – Living for the future
Where is the energy coming from in this circuit?
Battery
Describe how the electrons move around the
circuit. (This is easy – don’t think too hard!)
They go around in one direction.
This type of current is called DC. What is this
know as?
a. Dependent current
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b. Direct current
c. Diverted current
Look at the picture of this satellite, where
does it get its power from?
The Sun
These panels are called photocells. They
convert light into electrical energy. The
light knocks electrons free which creates a
DC current.
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The electrical energy from a photocell
depends on what factors?
Surface area of the photocell
Distance from the light source
Give two advantages of photocells:
Tough / renewable / use them in remote
locations / no pollution
Name two types of renewable energy:
Wind / wave / tidal / solar / biomass /
geothermal
Why is coal a type of non-renewable energy?
Coal takes millions of years.
Describe how
electricity is
made inside a power station:
Coal is burned  heats up water  turns water
into high pressure steam  steam turns the
turbine  turbine turns the generator 
generator makes electricity.
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Electricity is transported all over the country via
the national grid.
Electricity is carried away from power stations
along cables called transmission lines. The
transmission lines carry electricity at a very high
voltage. The current is low so the transmission
lines are heated up less. Because less heat
(energy) is lost – this reduces costs for the
company / consumer.
The electricity is passed through a
transformer to increase its voltage to several
hundred thousand volts. Later another transformer
reduces the voltage to a safe 230 V.
Look the following diagram:
What type of energy is stored in coal?
Chemical
How is the energy from the coal released?
It is burned
What two types of energy has the steam
got?
Kinetic / heat
What type of energy does the turbine
have?
Movement
What does the generator make?
Electricity
1. An electric fire needs 2 kW. It is switched on for 3 hours. If each kWh
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costs 10p, how much does it cost to run the fire?
cost = Power x time x cost of 1kWh
2kW x 3hrs x 10 p = 60 pence
2. A TV needs 250 W. It is switched on for 30 minutes (0.5 hrs). If each kWh
costs 8p, how much does it cost to run the TV? 250 x 0.5 x 8 = 1000 pence
3a. Write down the meaning of each symbol
P
V
I
Power(P), Voltage (V), Current (I)
3b. Calculate the voltage of a 72 watt laptop. The
laptop draws a current of 6 A.
V = P ÷ I= 12 V
Earth’s magnetic field
Draw the field lines of the Earth’s magnetic field. Take care when doing
this. Be as accurate as possible.
South Pole
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North Pole
Notice how the arrows point from north to south.
In what way is the Earth’s magnetic field similar to a magnet?
It has a north and a south pole.
Where does the magnetic field, of the Earth, come from?
Large electrical currents set up in the liquid iron core as the Earth spins.
Where did the Moon come from?
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A planet the size of Mars collided with the Earth.
Some matter from the impact came of the Earth –
this eventually clumped together to form the Moon.
What is a solar flare? Page 201
Vast clouds of charged particles ejected from the Sun
What problems can solar flares cause?
Destroy the electrical circuits inside a satellite.
Key words
Match up the definition and key word
Orbit
The distance light travels in one year
Centripetal force
The path of a planet around a star
Light year
The force that acts towards the centre of an orbit
Planetary nebula
Stars are made here. Huge clouds of gas and dust.
Draw the voltage-time graphs for a generator and a battery: Page 189
DC Current (battery)
AC Current (generator)
voltage
voltage
time
time
The magnet of a generator spins at 3000 revolutions every minute. Work out
how many cycles there are every second. (This is called the period)
Period = 50 every second
Frequency = 1 ÷ period
Using the answer to the last question, find the frequency.
Frequency = 0.02 Hertz
What are the three types of radiation?
Alpha Beta Gamma
Which one is most dangerous?
Alpha
Which one can travel through thin aluminium?
Gamma
Which type of radiation is used to control the
thickness of paper?
Beta