Physics Syllabus Question

iLikePiano99

Basically I want to ask a question about the STS part of the syllabus, taking this for example:

On the "Sources of emf and electric current" part of it, in the STS it has these listed that you must know:

Sources of emf: mains, simple cells, lead-acid accumulator, car batteries, dry batteries, thermocouple.

So my question is do I just need to just know the names of them, in case I'm asked for examples or do I need to be able to describe how they work because in the physics book there are proper explanations? thanks for any help!

clartharlear

I would expect no more than a sentence on each.
Learn:
definitions
examples
the forms of energy involved (see below)
primary vs secondary (see below)

From the teacher's guide:

A source (or seat) of emf is a device in which
chemical, mechanical or some other form of
energy is converted into electrical energy, e.g. a
battery, an electric generator, etc. In a cell, for
example, chemical energy is converted into
electrical potential energy. This causes charge to
move in an external circuit whenever the
opportunity arises. The emf of a particular cell is
decided simply by its chemistry and does not
depend on its size. Emf is measured in volts.

Production of EMF
In an electrical circuit, if any other form of energy
is converted into electrical energy, an electromotive
force or emf is said to exist in that circuit.
An emf may be generated in a number of ways.
1. Chemical
Chemical energy is transformed into electrical
energy by the immersion of two dissimilar
conducting materials in an electrolyte, e.g. as in
the simple cell.
2. Thermoelectric
Heat energy is transformed into electrical energy
by heating one of the junctions formed by joining
two wires made from dissimilar metals, e.g. in the
thermocouple,
3. Electromagnetic
The energy stored in a magnetic field may be
combined with some kinetic energy, e.g. a moving
conductor, such that some of the kinetic energy is
transformed into electrical energy, e.g. plunging a
magnet into a coil of wire generates an emf in the
coil. This is the most practical method of obtaining
electrical energy and is used in all dynamoelectric
machinery.

A primary cell is capable of producing current as
soon as its constituent chemicals are put together.
Once the chemical reaction is finished, the cell is
exhausted and cannot be regenerated.
A secondary cell generally needs to be charged
before it can be used. Its chemical reactions take
place in one direction during charging and in the
opposite direction during use, i.e. during
discharging.

Eurovisionmad

We've always been told to know the names of them, know the difference between primary ans secondary cells and know the thermoelectric electromagnetic and chemical as means of producing EMF, but you wouldn't have to explain how a lead-acid accumulator works!