Here are 3 possible areas where pylons and overhead cables are not permitted and reasons why: 1. Dense urban areas - There is not enough space between buildings to run overhead lines safely. The lines could interfere with other structures. 2. National parks/protected natural areas - Overhead lines would interfere with scenic views and natural landscapes that these areas aim to preserve. 3. Near airports - Tall pylons and cables could pose a collision hazard for planes during takeoff and landing. Overhead transmission has lower installation costs but takes up more space. Underground cables require burying lines which is more expensive but has less visual impact. Safety is also a consideration as underground cables are protected from weather damage but may be prone

1. ELECTROMAGNETIC INDUCTION

2. What is electromagnetic induction?
Faraday’s law of E.I states that the e.m.f. induced in a conductor is proportional to the rate at which
magnetic fields lines are cut by the conductor.
Above: The induced e.m.f and current can be
increased by:
1. Moving the wire faster
2. Using a stronger magnet
3. Increasing the length of wire in the magnetic
field
Right:
1. Moving the magnet at a higher speed
2. Increasing the no of turns in the coil
3. Using a stronger magnet

3. To determine the induced current direction
using Lenz’s law: which states that an induced current always flow in a direction such that it opposes
the change which produced it.
Using Fleming’s right-hand rule:
Eddy currents: [from the word Eddy meaning of water, air, or smoke) move in a circular way.] An eddy
current is an electrical current induced in a piece of metal due to the relative motion of a nearby
magnet.
Eddy current is used in a metal detector, core of a transformer, induction heating, crack detection,
eddy current brakes, Electric meters (Electromechanical Induction Meters)
Read more at: http://www.askphysics.com/eddy-currents-applications/

4. Generators
• A generator (electrical) is a device that converts mechanical or chemical energy into electrical energy.
Generators often use motors, turbines, engines, cranks, pistons, or other sources of mechanical
energy. Likewise, generators may use chemicals or other materials that produce electricity when
mixed or ignited. Generators do not produce electricity itself, but simply produce a flow of electricity by
forcing electrons from an external source to flow through an electrical circuit. Generators are used for
a wide variety of purposes and are available in many different forms.
Simple a.c generator:
A Generator is a device
which converts mechanical
energy into electrical
energy. A.C Generator works
on the principle of
electromagnetic induction
(motional emf). In generator
an induced emf is produced
by rotating a coil in a magnetic field.
To increase the e.m.f. and current:
• Increase the number of turns on the coil
• Increase the area of the coil
• Use stronger magnet
• Rotate the coil faster

5. Mutual induction
The production of an electric potential in a circuit resulting from a change of current in a neighboring circuit.
Mutual induction lies behind the operation of transformers.
The induced e.m.f. at switch on/off is increased if:
• The core of the electromagnet goes right through the 2nd
coil.
• The number of turns on the 2nd coil is increased
The simple transformer:
A transformer is an electrical device that transfers electrical
energy between two or more circuits through electromagnetic
induction. Electromagnetic induction produces an
electromotive force within a conductor which is exposed to
time varying magnetic fields. Transformers are used to
increase or decrease the alternating voltages in electric power
applications.

6. Transformer equation:
Step up transformer:
Step down transformer:
Transformer power equation:
Efficiency:

7. Power transmission
Activity question:
Pylons and overhead cables are not permitted
In some areas.
1. Name 3 of such areas
2. Give reasons why pylons and overhead
cables are not allowed in these areas.
3. Compare overhead and underground high
voltage transmission.