#3.1.2a(i)
current as the flow of charged particles
#3.1.2a(ii)
potential difference as energy per unit charge
#3.1.2a(iii)
resistance and conductance, including series and parallel combinations
#3.1.2a(iv)
the effect of internal resistance and the meaning of e.m.f.
#3.1.2a(v)
dissipation of power in electric circuits
#3.1.2a(vi)
the relationship between potential difference and current in ohmic resistors (Ohm’s law)
#3.1.2a(vii)
the action of a potential
#3.1.2a(viii)
simple electrical behaviour of metals, semiconductors and insulators in terms of the number density of mobile charge carriers
#3.1.2a(ix)
conservation of charge and energy.
as represented by Kirchhoff’s first and second law
#3.1.2b
Make appropriate use of:
(i) the terms: e.m.f, potential difference, current, charge, resistance, conductance, series, parallel, internal resistance, load, resistivity, conductivity, charge carrier number density
(ii) and recognise standard circuit symbols
by sketching and interpreting:
(iii) graphs of current against potential difference and graphs of resistance or conductance against temperature for ohmic and non-ohmic devices or components.
#3.1.2c(i)
\(R = \dfrac{V}{I} \), \(G = \dfrac{I}{V} \),
\(V = \dfrac{W}{Q} = \dfrac{P}{I} \),
\(P = IV = I^2R \),
\(W = VIt \),
\(V = ε - Ir_{internal} \)
Learners will also be expected to recall the equations for R and G.
Epsilon is used as the symbol for e.m.f. to avoid confusion with E which is used for energy and electric field. The ASE guide ‘Signs symbols and systematics’ details E as the correct symbol for e.m.f. and this will be credited in all examinations.
#3.1.2c(ii)
\(I = \dfrac{ΔQ}{Δt} \),
\(\dfrac{1}{G} = \dfrac{1}{G_1} + \dfrac{1}{G_2} + ...\)
\(G = G_1 + G_2 + ...\)
\(R = R_1 + R_2 + ...\)
\(\dfrac{1}{R} = \dfrac{1}{R_1} + \dfrac{1}{R_2} + ...\)
#3.1.2c(iii)
\(R = \dfrac{ρL}{A} \); \(G = \dfrac{σA}{L} \)
#3.1.2c(iv)
simple cases of a potential divider in a circuit using:
\(V_{out} = \dfrac{R_2}{R_1+R_2} × V_{in} \) and
\(\dfrac{V_1}{V_2} = \dfrac{R_1}{R_2}\)
Learners will be expected to recall the proportionality of potential difference and resistance in a series circuit
#3.1.2d(i)
investigating electrical characteristics for a range of ohmic and non-ohmic components using voltmeters and ammeters
links to 3.1.2a(vi), b(iii), PAG3
#3.1.2d(ii)
determining the resistivity or conductivity of a metal
links to 3.1.2c(iii), PAG3
#3.1.2d(iii)
use of potential divider circuits, which may include sensors such as thermistor, LDR
links to 3.1.2a(vii), PAG4
#3.1.2d(iv)
the calibration of a sensor or instrument
links to 3.1.2a(vii), c(iii), PAG3
#3.1.2d(v)
determining the internal resistance of a chemical cell or other source of e.m.f.
links to 3.1.2a(iv), PAG3