A bar magnet with its north pole facing a narrow, circular conducting coil of resistance 2Ω is moved along the common axis of the two.
(i) State Lenz’s law.
(ii) The magnet is pushed steadily towards the coil. Seen from the magnet side, what is the direction of the induced current in the coil? Give a clear justification.
(iii) After coming momentarily to rest, the magnet is pulled straight back along the same line. What is now the direction of the induced current? Explain your answer.
(iv) Account qualitatively for the mechanical work that must be done by the experimenter in both (ii) and (iii). How does this illustrate the principle of conservation of energy?