Material for thought
The students' answers to these three diagnostic questions are thought-provoking. In general terms the students are able to predict correctly what will happen physically in a circuit when changes are made, but they seem much less secure in providing correct explanations for those changes. Perhaps this is to be expected. Developing scientific explanations using concepts such as charge, current, energy and potential difference correctly is quite a challenge. With this in mind, it will do no harm, when returning to this topic, to get the rope loops out once again and to
go back to basics in helping students to visualise and model the working of electric circuits.
Teacher: Circuits are loops containing charged particles, all (nearly simultaneously) set in a steady average motion as a result of the action of cells and resistances in each loop.
We now turn our attention to electric current in simple loops. The fundamental teaching and learning challenge addressed here is for students to come to recognise that the size of the current in a simple electrical loop depends on the potential difference across the cell and the resistance of any component in the loop.