Q5 Read the following passage and answer the following questions. The scientist whose research would unite electricity and magnetism was Michael Faraday. He developed the first electric motor in 1821, showing that a current-carrying conductor could be made to revolve around a magnet. He went on to expand on Oersted’s observation that an electric current produces a magnetic effect. Perhaps, Faraday thought, the opposite was also true: a moving magnetic field could generate an electric current.This was to be called electromagnetic induction.Soon he had created the first electric generator,and everyday life would never be the same again.His experiments with induced currents produced the transformer.
(Adapted from Milestones of Science, Curt Supple, 2000)
(i) List three factors that affect the force on a current-carrying conductor placed near a magnet. (7) (ii) What energy transformation takes place in an electric motor? (iii) What is the function of a commutator in a d.c. motor? (iv) Draw a sketch of the output voltage from an a.c. generator.
(v) How are the slip rings connected to an external circuit in an a.c. generator?
(vi) A transformer and an induction coil can both be used to change a small voltage into a larger voltage.What is the basic difference in the operation of these two devices?
(vii) Name the Irish physicist who invented the induction coil. (viii) Give two factors that affect the efficiency of a transformer.
