DC current

NEW ENGLISH SCHOOL Science Dept: AS – Physics Unit 2: Target Sheet 16/3/09 DC Electricity Statement ref Describe electric current as the rate of flow of charged particles and use the expression I = ∆Q / ∆t 2.4.50 Use the expression V = W/Q 2.4.51 Recognise, investigate and use the relationship between current, voltage and resistance, for series and parallel circuits, and know that these relationships are a consequence of the conservation of charge and energy 2.4.52 Investigate and use the expressions P = VI, W = VIt. Recognise and use related expressions eg P = I²R and P = V²/R 2.4.53 Use the fact that resistance is defined by R = V/I and that Ohm’s law is a special case when I a V 2.4.54 Demonstrate an understanding of how ICT may be used to obtain current-potential difference graphs, including non-ohmic materials and compare this with traditional techniques in terms of reliability and validity of data 2.4.55 Interpret current-potential difference graphs, including non-ohmic materials 2.4.56 Investigate and use the relationship R = ρl/A 2.4.57 Investigate and explain how the potential along a uniform current-carrying wire varies with the distance along it and how this variation can be made use of in a potential divider 2.4.58 Define and use the concepts of emf and internal resistance and distinguish between emf and terminal potential difference 2.4.59 Investigate and recall that the resistance of metallic conductors increases with increasing temperature and that the resistance of negative temperature coefficient thermistors decreases with increasing temperature 2.4.60 Use I = nqvA to explain the large range of resistivities of different materials 2.4.61 Explain, qualitatively, how changes of resistance with temperature may be modelled in terms of lattice vibrations and number of conduction electrons 2.4.62 New Terms : 1