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

Figure 1

The structure of a step up (above) transformer and a step down (below) transformer can be seen in figure 1. As the voltage decreases, current increases, and vice versa. The transformer changes the size of the voltage by having a different number of primary and secondary coils. If there are more secondary coils, it is a step up transformer and will increase the voltage. If there are more primary coils, it is a step down transformer and will decrease the voltage. (Also has an iron core. That's important.)

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

Most helpful video I've seen in a really long time, which hopefully works....

• Movement of magnet produces electromagnetic force 
• Movement + magnetism = current
• 2 slip rings make contact with 2 brushes with copper or carbon connected to an external circuit
• Coil rotates, one half upwards, other downwards
• This produces current in 1 direction
• As continues rotating, half moving upwards moves downwards, vice versa. This constant change results in AC
• Replacing slip rings with split ring produces DC because it reverses current when it is naturally going to reverse so it produces current in only one direction

More diagrams here

6.14 Describe how the force on a current-carrying conductor in a magnetic field increases with the strength of the field and with the current.

Two things that increase force on the wire (which is the "current carrying conductor") are:

• increasing strength of magnetic field
• increasing amount of current flowing

:)

6.12 Understand that a force is exerted on a current-carrying wire in a magnetic field, and how this effect is applied in simple d.c. electric motors and loudspeakers

A force is exerted on a current carrying wire - you see this if you put it between two ends of a U shaped magnet with a current through it. Depending on the direction of the current, it will either move up or down. 

In speakers (link to BBC bitesize), the current is constantly changing direction. This means the poles of the electromagnet change, and so the wire varies between moving up and down - the current varies with the music. The electromagnet moves back and forth, creating vibrations, generating sound waves whose frequency changes with the frequency of the current.

In simple DC motors (link to BBC bitesize) , as we know, the wire experiences a force when it is within a magnetic field, and it moves. The current needs to be reversed every half term, which is done by a split ring commutator, to keep it spinning. The momentum it gains after it has started spinning helps keep it going, too.

6.10 Sketch and recognise magnetic field patterns for a straight wire, a flat circular coil and a solenoid when each is carrying a current

Straight wire
Basically little circles around the wire. Direction determined with right hand grip. (fig 1)

Figure 1

Solenoid (coil of wire)

Sort of like a regular magnetic field...in a tube... (fig 2) Direction can be found with right hand grip.

Figure 2

Flat coil

Like a regular wire x2 with a line in the middle. Again, determined with right hand grip. (fig 3)

Figure 3

6.9 Describe the construction of electromagnets

A coil of wire with a soft iron core and a current running through it will induce a magnetic field.

WARNING: do not use the word "create" for magnetic field, you will not get the mark :(

6.8 Understand that an electric current in a conductor produces a magnetic field round it

An electric current in a conductor, such as a wire, produces a magnetic field around it. Fairly self explanatory point. (:

6.7 Describe how to use two permanent magnets to produce a uniform magnetic field pattern.

Hold two opposite poles very close to each other so they attract. This will make a uniform magnetic field :) kind of as if they were one magnet

6.6 Describe experiments to investigate the magnetic field pattern for a permanent bar magnet and that between two bar magnets

1. 

• Take a piece of paper and a compass
• Place a magnet in the middle of the paper
• Slowly move the compass around the magnet. Draw on the paper where the arrow points each time
• Repeat until shape of magnetic field forms
• MULTIPLE COMPASSES MAY BE USED

2.

• Take a sheet of paper, iron filings and a magnet
• Place magnet under paper
• Carefully pour iron filings onto paper
• Magnetic field shape should form
• Yay

6.5 Understand that magnetism is induced in some materials when they are placed in a magnetic field

Some materials can become magnetic when they are placed in a magnetic field as it aligns all the domains inside, forming poles. Can happen to Fe, Co and Ni.

6.4 Understand the term ‘magnetic field line’

Magnetic field lines show the direction of the magnetic field (north to south). Field is 3D, lines give an idea. MUST NEVER TOUCH WHEN DRAWING. Add arrows :)

6.3 Describe the properties of magnetically hard and soft materials

Soft magnetic materials

• loses its magnetism almost as soon as it leaves the magnetic field
• can be magnetized / demagnetized
• i.e. soft iron core
• i.e. in electromagnets

Hard magnetic materials

• retains its magnetic properties

6.2 Understand that magnets repel and attract other magnets and attract magnetic substances

Magnets attract / repel other magnets depending on their poles and attract magnetic substances, which consist of:

• iron (Fe)
• nickel (Ni)
• cobalt (Co)

and any alloys that contain those metals.

6.1 Use the following units: ampere (A), volt (V), watt (W).

Amp (A) - current

Volt (V) - voltage (surprise!)

Watt (W) - power