3d.1 Recall that a capacitor normally consists of two metal plates separated by an insulating material.
A
capacitor consists of two metal plate (shown in blue) on the diagram.
Between them is a non conducting material called the dialectric (shown
in green)
3d.2 Understand that a capacitor can store an electric charge, and that
its ability to store a charge (capacitance) depends upon the area of
the plates, their separation and the nature of the material between the
plates (the dielectric).
A capacitor can store an
electric charge. A larger charge can be stored by increasing the
surface area of the metal plates, reducing the distance between the
plates and changing the type of dialectric.
3d.3 Recall that larger values of capacitor may be of electrolytic
construction, which are polarised and must be correctly connected.
Larger capacitors are often constructed in the form of electrolytic capacitors.
These have a positive plate and a negative plate - usually clearly
marked on the outside of the capacitor. In between them is a liquid electrolyte. It is important that they are
connected the right way. Over time the liquid electrolyte can dry up.
Structure of a capacitor
Inductors
3e.1 Recall that a current passing through a wire forms a magnetic field around the wire.
Recall that an inductor is normally a coil formed of a number of turns of wire to concentrate the magnetic field.
Recall that an inductor is able to store energy in its magnetic field.
When a an electric current flows through a wire a magnetic field is created around the wire (shown in red in the drawing)
Inductors
Recall that the ability to store energy is known as inductance, which
depends upon the number of turns of wire on the coil and its
dimensions.
An inductor
normally consists of a coil of wire. This increases the strength of the
magnetic field when the switch is closed (shown by the red lines on the
drawing). Energy is stored in this magnetic field, but only for a short time in a DC circuit.
This ability to store energy is called Inductance. the inductance can be increased by increasing the number of turns on the coil and by increasing the size of the coil.
