6.1  Capacitors

6.1.1  Capacitors

Learners should be able to demonstrate and apply their knowledge and understanding of:

(a) capacitance; C =Q/V  ; the unit farad

(b) charging and discharging of a capacitor or capacitor plates with reference to the flow of electrons

(c) total capacitance of two or more capacitors in series;

(d) total capacitance of two or more capacitors in parallel; C = C1 + C2 + ...

(e) (i) analysis of circuits containing capacitors, including resistors

(ii) techniques and procedures used to investigate capacitors in both series and parallel combinations using ammeters and voltmeters.

6.1.2  Energy

Learners should be able to demonstrate and apply their knowledge and understanding of:

(a) p.d. –charge graph for a capacitor; energy stored is area under graph

(b) energy stored by capacitor;

(c) uses of capacitors as storage of energy

6.1.3  Charging and discharging of capacitors

Learners should be able to demonstrate and apply their knowledge and understanding of:

(a) (i) charging and discharging capacitor through a resistor

(ii) techniques and procedures to investigate the charge and the discharge of a capacitor using both meters and data-loggers

(b) time constant of a capacitor–resistor circuit;

(c) equations of the form      and   for capacitor–resistor circuits

The x in this equation can stand for the current, voltage or charge.  The form of the equation stays the same.

(d) graphical methods and spreadsheet modelling of the equation      for a discharging capacitor

(e) exponential decay graph; constant-ratio property of such a graph.