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Electricity and Magnetism

  • A lot of this section is about the simple circuit but we will also tackle difficult ones. Difficult problems can often be split into simple steps.
  • What is the difference between EMF and PD?
  • Why is charge positive and negative?
  • How are magnetic and electric fields similar and how are the different?
  • How does an electric motor work?


  • Magnetic fields

    Why is the North pole actually a South? Why do we define magnetic field in terms of rotation not acceleration? What is the connection between magnetic fields and electric current? Why don't magnetic waves exist without electric waves?

  • Electric fields

    Electric force can not be explained without introducing a new quantity charge. You might think that this should be a fundamental quantity but it isn't, the fundamental unit of electricity is current. As with gravitational fields, field lines are used to

  • Moving charge in a magnetic field

    It's not often that you can impress your friends with your knowledge of physics but when the Northern lights appear everyone wants to know how they are formed.

  • Electric field lines

     Field lines not only show the direction of the force experienced by a small test charge but also the size. When drawing field lines make sure they start on a + and end on a -. Draw them carefully or you will throw away marks.

  • Magnets

    Magnetic fields are defined in terms of the rotation of a small magnetic dipole, this makes them quite different to electric and gravitational fields.

  • Series resistors

         Not all circuits are this simple but a lot can be broken down into components that are.