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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?


  • EMF

    A battery converts chemical energy to electrical energy but how it does that is one of the mysteries explained by Chemistry.

  • 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.

  • Kirchoff's Laws

     Kirchoff's laws are very useful for solving complex circuit problems but are based on simple conservation principles.

  • Current

    Electrons flow from low potential to high potential (uphill), this is not very intuitive so we consider conventional current that flows downhill.

  • Force on current carrying conductors

    An easy way to remember Which hand to use is that the left hand rule is applied to motors and motors drive on the left, What do you mean motors don´t drive on the left?

  • Measuring Voltage

     Ideally a voltmeter has infinite resistance and an ammeter zero resistance. Real meters are close but not perfect.