GCSE Physics Specification

OCR B J259

Section P3.2: What determines the current in an electric circuit?

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#P3.2.1

recall that current is a rate of flow of charge, that for a charge to flow, a source of potential difference and a closed circuit are needed and that a current has the same value at any point in a single closed loop

#P3.2.2

recall and use the relationship between quantity of charge, current and time:

charge (C) = current (A) × time (s)

#P3.2.3

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

#P3.2.4

a) recall and apply the relationship between I, R, and V, to calculate the currents, potential differences and resistances in d.c. series circuits:

potential difference (V) = current (A) × resistance (Ω)

b) describe an experiment to investigate the resistance of a wire and be able to draw the circuit diagram of the circuit used
PAG7

#P3.2.5

recall that for some components the value of R remains constant (fixed resistors) but that in others it can change as the current changes (e.g. heating elements, lamp filaments)

#P3.2.6

a) use graphs to explore whether circuit elements are linear or non-linear and relate the curves produced to their function and properties

b) describe experiments to investigate the I-V characteristics of circuit elements. To include: lamps, diodes, LDRs and thermistors. Be able to draw circuit diagrams for the circuits used
PAG6

#P3.2.7

represent circuits with the conventions of positive and negative terminals, and the symbols that represent common circuit elements, filament lamps, diodes, LDRs and thermistors, switches and fixed and variable resistors