## Overview This topic begins by defining magnetic flux and then explores the laws of Faraday and Lenz. Learners will apply these laws to determine the emf induced in a linear conductor moving at right angles to a magnetic field. The topic concludes with the derivation of the instantaneous emf induced in a coil rotating in a magnetic field. ## Working Scientifically There are opportunities within this topic for learners to solve problems set in practical contexts; to apply scientific knowledge to practical contexts; to present data in appropriate ways; to plot and interpret graphs. ## Mathematical Skills There are a number of opportunities for the development of mathematical skills in this unit. These include understanding and using the symbols: =, <, <<, >>, >, ∝, ≈; applying the concepts underlying calculus (but without requiring the explicit use of derivatives or integrals) by solving equations involving rates of change, for example x x t   = −  using a graphical method or spreadsheet modelling; visualising and representing 2D and 3D forms, including representations of 3D objects. ## How Science Works There is an opportunity within this topic for learners to use theories, models and ideas to develop scientific explanations. Learners can consider the applications and implications of science and the associated benefits to society by studying the application of Faraday’s law to the case of a rotating coil in a magnetic field. They can consider how the invention of devices such as the a.c. generator has benefitted society. Lenz’s law gives learners the opportunity to answer scientific questions and solve scientific problems. ### Learners should be able to demonstrate and apply their knowledge and understanding of: (a) the definition of magnetic flux as   = ABcos and flux linkage = N (b) the laws of Faraday and Lenz (c) how to apply the laws of Faraday and Lenz (i.e. emf = - rate of change of flux linkage) (d) the idea that an emf is induced in a linear conductor moving at right angles to a uniform magnetic field (e) qualitatively, how the instantaneous emf induced in a coil rotating at right angles to a magnetic field is related to the position of the coil, flux density, coil area and angular velocity