Charge and Energy

Introduction to Electricity and Circuits

In this course, Professor David Berman (Queen Mary University of London) explores charge, energy, and circuits at a GCSE level. In the first mini-lecture, we look at charges, the force a charge experiences in an electric field, potential energy, potential difference (or ‘voltage’), and energy (or ‘work done’). In the second mini-lecture, we introduce current as the flow of charge and define it mathematically before going through a couple of examples. The third mini-lecture delves into circuits, introducing the concept of circuit diagrams, resistance and resistors, and Ohm’s Law, followed by a few examples. In the fourth mini-lecture, we discuss properties of current, voltage, and resistance in circuits and introduce the series circuit, a circuit with only one path that the current can take. The fifth mini-lecture introduces parallel circuits as circuits in which the current can take more than one path through the circuit, and then goes through an example, concluding with the equation for resistors in parallel.

Charge and Energy

In this first mini-lecture we introduce the concept of a charge in an electric field, focusing in particular on: (i) the equation F = q × Electric Field Strength, where F is the force a change feels in an electric field and q is the charge measured in units of Coulombs (C); (ii) familiar objects that create electric fields; (iii) charges, which are either positive or negative, for example the electron which is negative; (iv) the potential energy = Fd, where F is a constant force and d is the distance travelled; (v) the potential difference, or voltage, which is the potential energy per unit charge in some electric field and is measured in units of volts (V); (vi) the energy (E), or ‘work done,’ which is given by E = qv; and (vii) a couple of examples that use E = qv.