8.3 Electrical
Energy in the Home
Richard
Newbury,
School of Physics - UNSW,
November 1999.
1.
Society has become increasingly dependent on electricity
over the last 200 years
2. One of the
main advantages of electricity is that it can be moved
with comparative ease from one place to another through
electric circuits
3. Series
and parallel circuits serve different purposes in households
4. The amount
of energy transformed in an appliance is related to the
power rating of an appliance and the length of time it
is used
5. Electric
currents also produce magnetic fields and these fields
are used in different technologies in the home
1.
Society has become increasingly dependent on electricity
over the last 200 years
- discuss how the
main sources of domestic power have changed over time
- assess some of
the impacts of changes in and increased access to, sources
of power for a community
- discuss some of
the ways in which electricity can be provided in remote
locations
• Skills
analyse secondary
information about one of the debates that took place to
develop our current understanding about electricity from
one the following:
- p Volta and Galvani and
their debate over animal and chemical electricity
- p Faraday
- p Ohm
• Useful Sites
Many good pages with historical
perspective:
(these sites discuss ‘leaking
electricity’ and address power consumption and ways
in which it can be reduced.)
• Simple Demonstrations/Class
Experiments
Construct series of ‘Volta
cells’ using plastic cups, zinc & copper sheet,
lemon juice electrolyte — can light a red LED with
a few of these in series!
2. One of
the main advantages of electricity is that it can be moved
with comparative ease from one place to another through
electric circuits
- discuss qualitatively how
each of the following affects the movement of electricity
through a conductor:
- p length
- p cross-sectional area
- p temperature
- p material
• Skills
present diagrammatic information
to describe the electric field strength and direction of
- p a single charged object
- p parallel plates
- p a positive and negative
charge
•Useful Sites
A good starting point is
3. Series
and parallel circuits serve different purposes in households
- explain why there are different
circuits for lighting, heating and other appliances
in a house
• Skills
construct model household circuits
using electrical components
• Problem
Actually, household wiring has
few series circuits so the household is not necessarily
a strong pedagogical example.
• Useful Sites
• Demonstrations/experiments
A complete ‘recipe’
for setting up series/parallel circuit demonstrations for
students can be found at http://www.iit.edu/~smile/ph9113.html
4.
The amount of energy transformed in an appliance is related
to the power rating of an appliance and the length of time
it is used
- describe the relationship
between power dissipated, potential difference and current
- explain the relationship
Energy — VIt
- explain why a simple scale
has been used for energy rating on commercial goods and
how these scales relate to potential difference and current
• Skills
discuss ways in which electrical
consumption in households could be reduced
• Useful Sites
• Demonstrations/Experiments
First hand investigation of
an electric heating coil using ‘homemade" resistance
wire coil, lab thermometer. See UNSW School of Physics suppliers
page at
www.phys.unsw.edu.au/hsc
5.
Electric currents also produce magnetic fields and these
fields are used in different technologies in the home
- assess the impact of applications
of magnetic field on society
• Skills
explain an application of magnetic
fields in pest control
• Problems
Electromagnetic field is more
relevant here. Most electronic pest control devices claim
to operate via ultrasonics, those using hybrid ultrasonic/electromagnetic
principle are far fewer and suspect.
• Useful Sites
• Demonstrations/Experiments
Simple, inexpensive electromagnets
can be wound with insulated copper wire on an iron rod (nail).
Can be used to pick up specified weight (paper clips?).
Again see
Further Information
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