P3: Electricity

P3.1 Static and charge

PM3.1i: recall and apply: charge flow (C)= current (A) x time (s)

P3.1a describe that charge is a property of all matter, that there are positive and negative charges, but the effects of the charges are not normally seen as bodies containing equal amounts of positive and negative charge so their effects cancel each other out

P3.1b describe the production of static electricity, and sparking, by rubbing surfaces, and evidence that charged objects exert forces of attraction or repulsion on one another when not in contact

P3.1c explain how transfer of electrons between objects can explain the phenomena of static electricity

P3.1d explain the concept of an electric field and how it helps to explain the phenomena of static electricity

P3.1e recall that current is a rate of flow of charge (electrons) and the conditions needed for charge to flow

P3.1f recall that current has the same value at any point in a single closed loop

P3.1g recall and use the relationship between quantity of charge, current and time

P3.2 Simple circuits

PM 3.2i: recall and apply: potential difference (V)= current (A) x resistance (Ω)

PM3.2ii: recall and apply: energy transferred (J) = charge (C) x potential difference (V)

PM3.2iii: recall and apply: power (W) = potential difference (V) x current (A) = (current (A))2 x resistance (Ω)

PM 3.2iv: recall and apply: energy transferred (J, kWh) = power (W, kW) x time (s, h) = charge (C) x potential difference (V)

P3.2a describe the differences between series and parallel circuits

P3.2b represent d.c. circuits with the conventions of positive and negative terminals, and the symbols that represent common circuit elements

P3.2c recall that current (I) depends on both resistance (R) and potential difference (V) and the units in which these are measured

P3.2d recall and apply the relationship between I, R and V, and that for some resistors the value of R remains constant but that in others it can change as the current changes

P3.2e explain that for some resistors the value of R remains constant but that in others it can change as the current changes

P3.2f explain the design and use of circuits to explore such effects

P3.2g use graphs to explore whether circuit elements are linear or non-linear (M4c, M4d)

P3.2h use graphs and relate the curves produced to the function and properties of circuit elements (M4c, M4d)

P3.2i explain, why, if two resistors are in series the net resistance is increased, whereas with two in parallel the net resistance is decreased (qualitative explanation only)

P3.2j calculate the currents, potential differences and resistances in d.c. series and parallel circuits

P3.2k explain the design and use of such circuits for measurement and testing purposes

P3.2l explain how the power transfer in any circuit device is related to the potential difference across it and the current, and to the energy changes over a given time

P3.2m apply the equations relating potential difference, current, quantity of charge, resistance, power, energy, and time, and solve problems for circuits which include resistors in series, using the concept of equivalent resistance (M1c, M3b, M3c, M3d)