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Alternator = every half turn current switches direction. Produces AC
Dynamo = same set up as an alternator, at end of coil there is a commutator, every half turn it switches the sign of the current so remains positive. Produces DC
Transformers = AC in first coil creates changing magnetic field, cuts through secondary coil and induces current In the secondary coil which is also AC

DC = direct current
AC = alternating current
Transformer summary = Step-up increase voltage, Step-down decrease voltage

National grid... electrical energy is transferred at high voltages from powers stations to improve the effeciency of transmission, larger the current the greater heating and more energy lost from the system. So reducing voltage and reduces current and saves energy. Dangerous near villages though, high voltage contact = death

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Each component is at 90 degrees to the others, use this to work out the unknown factor out of the three
Remember current moves in opposite direction to electron flow

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Like poles repel, opposite attract. Cobalt/steel/ion magnetic materials
Permanent magnets always magnetic and have poles like in compasses
Induced magnets are materials that come magnetic but not fixed poles. Stroke them with a permanent magnet and it aligns all domains in same direction creating temporary magnet

Magnetic field always point North to South. Field strength decrease was from the magnet, smaller the spacing between the magnet the stronger the magnetic

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Learn key symbols.
Types of circuits series and parallel. Series are closed and the current is the same eberywehre
Parrael is branded cituict and current split into multiple paths, total current = total current in all of the branches added together
Potential difference (Voltage) is measured across two points, measured with a voltmeter that is placed parallel.
Current (I) is measured in amps and is the rate flow of charge, flow of electrons in wires, measured with Ammeter connected in the series
Resistance is the ability to stop the flow of current, great this is the harder it is for the charge to flow

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3 different wires all different purpouses
LIVE is brown, carries voltage from mains to appliance
NEUTRAL is blue, completes the circuit
EARTH wire is yellow/green and is safety wire to stop the appliance becoming live
Fuse is connected to live wire and can heat up and blow if too much current

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Objective interactions can be without contact or with.
Without = Gravitational attraction between two objects with mass and larger mass gives greater attraction
With = Friction, surfaces that are rough and rubbed together cause friction when moved

Scalar quantity has just size so direction plays no part in describing it, so mass, distance
Vector has size and direction, like velocity a speed in a certain direction, weight

Vector diagrams will show forces acting upon an object, be able to describe them and how they change over time for example a skydiver leaving the aircraft. You will calculate the resultant force so find the difference and if arrows are equal in size this means equilibrium and no change.

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Energy is never created or destroyed just transferred.
We get useful and wasteful energy.

We use our microwave to heat food, but at the same time we get light energy, we don't use it for the light energy this is wasteful, we just want the thermal energy.

Diagrams will show useful and wasted energy so will have to calculated effeciency
Efficiency is a measure of useful energy. Useful / total energy x 100
Example - Turn on a lightbulb and get light and heat, light is useful and heat is wasted.

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Key equations for the exam (will be on the equation sheet)

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Key equations for the exam (will be on the equation sheet)

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Speed = distance / time
Acceleration = change in velocity / time
Force = mass x acceleration
GPE = mass x gravitation field str (10N/kg) x change in height
Kinetic energy = 1/2 x m x velocity squared
Momentum P = mv      (mass x velocity)
Efficiency = useful energy / total energy x 100

Work done (J) = force (Newton) x distance (meters)
Power (Watts )= energy transferred (J) / time (s)

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Motor effect occurs when a wire with a current flowing through it is placed in a magnetic field and experiences a force
This effect is a result of two interacting magnetic field
One is made around the wire due to current flowing through it and the second field which wire is placed lies between the two magnets

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We have different sources, fossil fuels, tidal, solar, wind.
When comparing remember, fossil fuels are non-renewable, they will run out. They give us large amount of energy but release greenhouse causes which cause pollution.

The renewable sources tidal, solar and wind will not run out, they do not cause pollution but produce less energy and are usually expensive. For solar panels we need sunny climate to work!

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1st law = an object will remain in motion unless a net force acts upon it. If an object is at rest it will remain at rest until force is applied
2nd law = the more force you apply, the greater the acceleration
3rd law = every action has a reaction force. Example, a Rocket ejects 800 kJ of energy, it will move 800 kJ worth of energy in the air

'Resultant force' just means overall force, find the difference of the forward and backwards force and this is it.

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Rabbits mate in very unusual expensive gardens
Radio, microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma

You need to know uses, and high/low frequency and wavelength.
Radio has lowest frequency highest wavelength. Gamma has highest frequency lower wavelength.

Uses, radio for TV, microwave for cooking food, Infrared use in night Vision goggles, X-ray for looking into body and bones, Gamma to treat cancer.

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Thinking time is how long it takes a person to response to a situaiton
Breaking time/distance is how long or how far it takes a vehicle to stop after pressing the breaks

Thinking distance is affected by concentration, tiredness, alcohol, distractions
Braking distance is affected by speed, icy/wet roads, bad brake pads

Remember, heavier car with more people, more kinetic energy, more force to stop the car, more distractions and longer thinking and breaking time

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Isotopes are the same elements, they have DIFFERENT NEUTRONS ONLY. Protons and electrons stay same.
These are unstable sometimes and will emit energy in the form of radiation. Radiation is harmful to humans can cause cancer by mutated cells.

We measure radiation with photographic badges for doctors/radiologists to monitor radiation, darker it goes more exposure, or we use a Geiger-Muller counter. More ticks, higher level of radiation

Main types of radiation are Alpha, Beta and Gamma. Gamma
When these decay, remember, for Alpha the top number goes down by 4 and bottom number by 2.
For Gamma radiation, nothing changes so original element stays same.

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Parts of a wave
Frequency = number of waves that pass per second
Amplitude = the waves height
Wavelength = the distance between two parts of the wave, the length of 1 full wave

When waves pass through one material to another, they change direction this is called 'Refraction'. Speed and wavelength decrease.

Speed of a wave = frequency x wavelength

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'Half-life' is the time it takes half the amount of a radioactive to decay. If the half life is 5 hours, and we leave the sample for 15 hours, then the sample has gone through 3 half lives.

So, if we started with 80g of the sample, 3 half lives would leave... 80 > 40 > 20 > 10g at the end
Half the same 3 times! Graph questions come here, read of half the total value on the axis and read across