6.20 know and use the relationship: input power = output power

input power = output power
VP IP = VS IS

(primary voltage x primary current = secondary voltage x secondary current)

This is only true if we assume that something is 100% efficient and has lost no energy in other forms (like heat)

6.19 know and use the relationship between input (primary) and output (secondary) voltages and the turns ratio for a transformer

primary voltage/ secondary voltage = primary turns/ secondary turns

^Vp/_Vs = ^Np/_Ns

6.18 explain the use of step-up and step-down transformers in the largescale generation and transmission of electrical energy

In the national grid (the system which delivers electricity around the country) transformers are used. Because the wires are long there is more resistance, so a high current will cause a lot of heat; which is dangerous and looses a lot of energy. When electricity leaves a power plant, a step up transformer is used, this means the voltage is high, but the current is low. When electricity reaches a home or business it is stepped down to make it useful in appliances that we use, the wires are shorter so less of a danger is presented by this.

bpbtecscience

6.17 describe the structure of a transformer, and understand that a transformer changes the size of an alternating voltage by having different numbers of turns on the input and output sides

A transformer is used to change the current and voltage of electricity.

A current carrying wire is wrapped round one side of a transformer, another wire is wrapped round the other. There will be the same amount of power on both sides, but one will have a higher voltage and lower current the other a lower voltage and a higher current.

The transformer is made of iron, this is because it is a soft metal and can be turned on and off as a magnet: the current from the first wire induces a magnetic field in the transformer, this then induces a current in the second wire.

More coils causes more higher voltage (and lower current.) So if the second side has more turns of wire wrapped round the transformer it will step the voltage up (step up transformer.) If the second side has less turns, the voltage will be stepped down (step down transformer.)

scicenceaid

6.16 describe the generation of electricity by the rotation of a magnet within a coil of wire and of a coil of wire within a magnetic field and describe the factors which affect the size of the induced voltage

rotate a magnet in a coil of wire and there will be a current induced, the same is true for rotating a coil of wire in a magnetic field.

Factors that increase the electricity generated include: strength of magnetic field; number of coils in wire; speed of rotations.

6.15 understand that a voltage is induced in a conductor or a coil when it moves through a magnetic field or when a magnetic field changes through it and describe the factors which affect the size of the induced voltage

If you move a wire back and forth across a magnetic field a voltage will be induced.

If you move a magnet back and forth through a coil of wire a voltage will be induced.

If you increase the magnetic field strength, quicken the movement or increase the coils of wire you can increase the voltage induced!