Everything you need to know about transformers at IGCSE level :)

HideShow resource information
  • Created by: BusyGirl
  • Created on: 11-11-12 23:21

First 188 words of the document:

A transformer is a device that steps-up or steps-down an
alternating voltage from the primary coil to the
secondary coil.
Circuit symbol for a transformer:
How a transformer works:
The primary coil is supplied with alternating voltage which sets up a varying magnetic field around the
coil and extends to the secondary coil. When the varying field cuts across the secondary coil, alternating
voltage is induced in the secondary coil.
*Transformers only work with a.c.
A step-up transformer:
Secondary coil has more turns than primary coil
Converts low voltage to high voltage
Converts high current to low current
A step-down transformer:
Secondary coil has fewer turns than primary coil
Converts high voltage to low voltage
Converts low current to high current
The ratio of the voltage of the secondary coil over the voltage of the primary coil to the number of turns
in the secondary coil over the number of turns in the primary coil is the same.
i.e. Vs/Vp = Ns/Np

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Energy losses in transformers:
Heat loss from the resistance in the winding of the coil: as current passes through the wire, heat
is released.
Eddy currents losses in the core: eddy currents are circulating currents induced in the core by
the magnetic field from the primary coil, producing heat.
Leakage of magnetic field: not all of the magnetic field from the primary coil reaches the
secondary coil so energy is lost.…read more

Page 3

Preview of page 3

Here's a taster:

How energy is transported:
The power station generates electricity with low voltage and high current, which is then stepped up to
be transported with high voltage and low current to reduce heat production in the transmission cables,
which are made from copper as it is a cheap and good conductor. This voltage is then stepped down for
domestic use.
Why transmission of electricity is cheaper if voltage is very high:
High voltage means low current so less heat loss from cables will occur.…read more




Similar Physics resources:

See all Physics resources »See all resources »