Wire - Magnetic Field - Solenoid - Electromagnet
13	How can a Straight Wire produce a Magnetic Field?	Answer
14	What is the Shape of the Magnetic Field around a Straight Wire?	Answer
15	How can the Magnetic Field Direction be Reversed?	Answer
16	What is a Solenoid?	Answer
17	What is the Shape of the Magnetic Field around a Solenoid?	Answer
18	How does Soft Iron inside a Coil make a Magnetic Field Stronger?	Answer
19	What is the Difference between a Temporary and a Permanent Magnet?	Answer
20	Give one Example of a use for a Permanent Magnet.	Answer
21	Give two Ways of Increasing the Strength of a Magnetic Field around a Coil.	Answer
22	Give one Example of a use for an Electromagnet.	Answer

Bell - Relay - Circuit Breaker - Residual Current Circuit Breaker
23	Describe how an Electric Bell works.	Answer
24	Give one Difference between the two Circuits of a Relay?	Answer
25	What is the Advantage of using a Relay?	Answer
26	Give one Example of a use for a Relay.	Answer
27	What does a Circuit Breaker do?	Answer
28	Describe how a Residual Current Circuit Breaker works.	Answer

Motor Effect - Commutator - Loudspeaker
29	Why does a Wire carrying a Current feel a Force in a Magnetic Field?	Answer
30	In which Direction is the Force?	Answer
31	In a Motor, why is one side of the Armature Pushed and the other Pulled?	Answer
32	What does a Split - Ring Commutator do?	Answer
33	Why is a Split - Ring Commutator needed in a Motor?	Answer
34	Why does the Coil in a Loudspeaker need Alternating Current?	Answer
35	Why does the Paper Cone in a Loudspeaker do?	Answer

Induced Current - Generator - Dynamo - Microphone
36	What is Induced Current?	Answer
37	When does Induced Current happen?	Answer
38	Give one Example of a use for Induced Current.	Answer
39	Give two Ways of Increasing the Strength of an Induced Current.	Answer
40	Give one Way of Reversing the Direction of an Induced Current.	Answer
41	What does a Generator do?	Answer
42	Why does a Generator produce Alternating Current?	Answer
43	Why are Slip Rings needed?	Answer
44	How does the Output of a Generator Change when it is turned Faster?	Answer
45	Why are Slip Rings not needed in a Bicycle Dynamo?	Answer
46	What makes the Magnet Rotate in a Bicycle Dynamo?	Answer
47	How does Sound produce Alternating Current in a Microphone?	Answer

Transformers - National Grid
48	What is a Transformer made from?	Answer
49	What can a Transformer do?	Answer
50	What is a Step Up Transformer?	Answer
51	Which Coil has More Turns of Wire in a Step Up Transformer?	Answer
52	What is the Transformer Equation?	Answer
53	Will a Transformer work with Alternating Current?	Answer
54	Will a Transformer work with Direct Current?	Answer
55	As the Voltage goes Up, What goes Down?	Answer
56	Why is Power Output less than Power Input for a Transformer?	Answer
57	What is the National Grid?	Answer
58	Why is Aluminium used for Cables Suspended from Pylons?	Answer
59	Give one Advantage for using Pylons?	Answer
60	Give one Disadvantage for using Pylons?	Answer
61	Why is a Step Up Transformer used at a Power Station?	Answer

Power Stations - Renewable - Non-Renewable
62	What does a Power Station do?	Answer
63	What does Renewable mean?	Answer
64	What does Non-Renewable mean?	Answer
65	What is a Turbine?	Answer
66	How do Fossil Fuels turn a Turbine?	Answer
67	To what is a Turbine connected to produce Electricity?	Answer
68	What is the Original Source of the Energy in Fossil Fuels?	Answer
69	Give two Advantages of using Fossil Fuels to produce Electricity.	Answer
70	Give two Disadvantages of using Fossil Fuels to produce Electricity.	Answer
71	How does Nuclear Power turn a Turbine?	Answer
72	Give two Advantages of Nuclear Power.	Answer
73	Give two Disadvantages of Nuclear Power.	Answer
74	How does Hydroelectric Power turn a Turbine?	Answer
75	What is the Original Source of the Energy in Hydroelectric Power?	Answer
76	Give two Advantages of Hydroelectric Power.	Answer
77	Give one Disadvantage of Hydroelectric Power.	Answer
78	How does Tidal Power produce Electricity?	Answer
79	What is the Original Source of the Energy in Tidal Power?	Answer
80	Give two Advantages of Tidal Power.	Answer
81	Give one Disadvantage of Tidal Power.	Answer
82	How does Wave Power produce Electricity?	Answer
83	What is the Original Source of the Energy in Wave Power?	Answer
84	Give one Advantage of Wave Power.	Answer
85	Give one Disadvantage of Wave Power.	Answer
86	How does Wind Power produce Electricity?	Answer
87	What is the Original Source of the Energy in Wind Power?	Answer
88	Give one Advantage of Wind Power.	Answer
89	Give one Disadvantage of Wind Power.	Answer
90	How does Solar Power produce Electricity?	Answer
91	What is the Original Source of the Energy in Solar Power?	Answer
92	Give one Advantage of Solar Power.	Answer
93	Give one Disadvantage of Solar Power.	Answer
94	How does Geothermal Power produce Electricity?	Answer
95	What is the Original Source of the Energy in Geothermal Power?	Answer
96	Give one Advantage of Geothermal Power.	Answer
97	Give one Disadvantage of Geothermal Power.	Answer
98	How does Biomass produce Electricity?	Answer
99	What is the Original Source of the Energy in Biomass?	Answer
100	Give one Advantage of using Biomass to produce Electricity.	Answer
101	Give one Disadvantage of using Biomass to produce Electricity.	Answer
102	How does The Sun make the Wind Blow?	Answer
103	How does The Sun make Water Waves?	Answer
104	How does The Sun make the Rain Fall?	Answer
105	How can we Reduce Energy Use?	Answer

http://www.gcsescience.com/pme42.htm

What is the governing equation for field strength relative to distance? For a circular magnet with a radius of R and Length L, the field at the centerline of the magnet a distance X from the surface can be calculated by the following formula (where Br is the Residual Induction of the material): Can a magnet that has lost its magnetism be re-magnetized? Provided that the material has not been damaged by extreme heat, the magnet can be re-magnetized back to its original strength. Can I make a magnet that I already have any stronger? Once a magnet is fully magnetized, it cannot be made any stronger - it is "saturated". In that sense, magnets are like buckets of water: once they are full, they can't get any "fuller". How do you measure the strength or power of a magnet? Most commonly, Gaussmeters, Magnetometers, or Pull-Testers are used to measure the strength of a magnet. Gaussmeters measure the strength in Gauss, Magnetometers measure in Gauss or arbitrary units (so its easy to compare one magnet to another), and Pull-Testers can measure pull in pounds, kilograms, or other force units. Special Gaussmeters can cost several thousands of dollars. We stock several types of Gaussmeters that cost between $400 and $1,500 each. If I have a Neo magnet with a Br of 12,300 Gauss, should I be able to measure 12,300 Gauss on its surface? No. The Br value is measured under closed circuit conditions. A closed circuit magnet is not of much use. In practice, you will measure a field that is less than 12,300 Gauss close to the surface of the magnet. The actual measurement will depend on whether the magnet has any steel attached to it, how far away from the surface you make the measurement, and the size of the magnet (assuming that the measurement is being made at room temperature). For example, a 1" diameter Grade 35 Neo magnet that is 1/4"long, will measure approximately 2,500 Gauss 1/16" away from the surface, and 2,200 Gauss 1/8" away from the surface. What are Magnetic Poles? Magnetic Poles are the surfaces from which the invisible lines of magnetic flux emanate and connect on return to the magnet. What are the standard industry definitions of "North" and "South" Pole? The North Pole is defined as the pole of a magnet that, when free to rotate, seeks the North Pole of the Earth. In other words, the North Pole of a magnet seeks the North Pole of the Earth. Similarly, the South Pole of a magnet seeks the South Pole of the Earth. Can a particular pole be identified? Yes, the North or South Pole of a magnet can be marked if specified. How can you tell which is the North Pole if it is not marked? You can't tell by looking. You can tell by placing a compass close to the magnet. The end of the needle that normally points toward the North Pole of the Earth would point to the South Pole of the magnet. What are the different types of magnets available? There are 2 types of magnets: permanent magnets and electro-magnets. Permanent magnets emit a magnetic field without the need for any external source of power. Electro-magnets require electricity in order to behave as a magnet. There are various different types of permanent magnet materials, each with their own unique characteristics. Each different material has a family of grades that have properties slightly different from each other, though based on the same composition. What are Rare Earth Magnets? Rare Earth magnets are magnets that are made out of the Rare Earth group of elements. The most common Rare Earth magnets are the Neodymium-Iron-Boron and Samarium Cobalt types. Which are the strongest magnets? The most powerful magnets available today are the Rare Earths types. Of the Rare Earths, Neodymium-Iron-Boron types are the strongest. However, at elevated temperatures (of approximately 150C and above), the Samarium Cobalt types can be stronger that the Neodymium-Iron-Boron types (depending on the magnetic circuit). What does 'orientation direction' mean? Most modern magnet materials have a "grain" in that they can be magnetized for maximum effect only through one direction. This is the "orientation direction", also known as the "easy axis", or "axis". Unoriented magnets (also known as "Isotropic magnets") are much weaker than oriented magnets, and can be magnetized in any direction. Oriented magnets (also known as "Anisotropic magnets") are not the same in every direction - they have a preferred direction in which they should be magnetized.

http://www.gcsescience.com/pme42.htm