## Overview This topic covers the concept of magnetic fields and investigates the forces on current carrying conductors and moving charges in magnetic fields. The magnetic fields due to currents and the force between current carrying conductors is investigated. Learners also study the deflection of beams of charged particles in electric and magnetic fields. ## Working Scientifically The specified practical work in this topic gives learners the opportunity to plot and interpret graphs; process and analyse data using appropriate mathematical skills; make and record observations; keep appropriate records of experimental activities; to use online and offline research skills including websites, textbooks and other printed scientific sources of information; to use a data logger with a sensor to collect information. ## Mathematical Skills There are a number of opportunities for the development of mathematical skills in this unit. These include recognising and using expressions in decimal and standard form; using an appropriate number of significant figures; identifying uncertainties in measurements and using simple techniques to determine uncertainty; substituting numerical values into algebraic equations using appropriate units for physical quantities; plotting two variables from experimental or other data; determining the slope and intercept of a linear graph; calculating rate of change from a graph showing a linear relationship; using angles in regular 2D and 3D structures; visualising and representing 2D and 3D forms; using sin, cos and tan in physical problems. ## How Science Works There are opportunities within this topic for learners to communicate information and ideas in appropriate ways using appropriate terminology; to consider applications and implications of science and evaluate their associated benefits and risks. Learners can study the motion of charged particles in magnetic fields to develop an understanding of how scientific knowledge and understanding develops over time. This understanding can lead to an appreciation, for example, of how charged particles behave in linear accelerators, cyclotrons and synchrotrons. This can help evaluate the role of the scientific community in validating new knowledge, for example, using the large hadron collider to reproduce the conditions which existed immediately after the Big Bang. ### Learners should be able to demonstrate and apply their knowledge and understanding of: (a) how to determine the direction of the force on a current carrying conductor in a magnetic field (b) how to calculate the magnetic field, B, by considering the force on a current carrying conductor in a magnetic field i.e. understand how to use F BIl = sin (c) how to use F Bqv = sin for a moving charge in a magnetic field (d) the processes involved in the production of a Hall voltage and understand that VH ∝ B for constant I (e) the shapes of the magnetic fields due to a current in a long straight wire and a long solenoid (f) the equations 2 o I B a   = and B nI = o for the field strengths due to a long straight wire and in a long solenoid (g) the fact that adding an iron core increases the field strength in a solenoid (h) the idea that current carrying conductors exert a force on each other and to predict the directions of the forces (i) quantitatively, how ion beams of charged particles, are deflected in uniform electric and magnetic fields (j) the motion of charged particles in magnetic and electric fields in linear accelerators, cyclotrons and synchrotrons [[Specified Practical Work]] - Investigation of the force on a current in a magnetic field - Investigation of magnetic flux density using a Hall probe