Science Electrical Principles and Technologies

• Input energy is energy consumed and output energy is amount of work done.

• Energy cannot be created or destroyed – only transformed from one form to another.

• Electrical –energy of charged particles released when they flow or discharge   (i.e. generator).

• Mechanical  - energy of moving objects or potential energy of objects that could move  (i.e.  motor).

• Thermal – energy of vibrating particles in a substance.  The faster the particles move, the more heat energy produced (i.e. heater).

• Chemical – potential energy stored in chemicals and released when there is a chemical reaction (i.e. battery).

• Devices used for common energy conversions:

• A transformer is an electrical device that takes electricity of one voltage (usually very high voltage power lines) and changes it into another voltage (usually lower voltage house current). You'll see transformers at the top of utility poles, in the green boxes in neighbourhoods and even changing the voltage in a toy train set. 

• Power

  
  

  • Power is a measure of the rate of doing work or the rate at which energy is converted.  Electrical power is the rate at which electricity is produced or consumed and depends on the amount of electric current flowing and the applied voltage.  How fast can something do work? Using the water analogy, electric power is the combination of the water pressure (voltage) and the rate of flow (current) that results in the ability to do work.  More pressure or more flow leads to faster work or more power.Step-up transformers increase voltage and step-down transformers decrease voltage.

• Energy efficiency  is the ratio between the useful output of an energy conversion device (heat, light, mechanical)  and the energy put into it.
  

• Energuide labels help us increase energy efficiency by showing us which devices are the most efficient before purchasing them.  

  1 - average number of kWh this appliance will use in a year

  2 - the black arrow above the bar tells you where your appliance rates

        compared to other models in Canada.

  3 - the bar shows the range of most efficient (564) to least efficient (972)

        kWh appliances of this type in Canada.

        

• Reducing friction is a good way of making energy more efficient.  You can reduce friction by:

•  using ball bearings

•  lubricants (oil or grease) 

• Or: fewer moving parts. Friction is the main cause of inefficiency through heat loss. This picture shows how ball bearings (little metal balls) that are placed between two pieces of metal can reduce the friction between moving parts since it decreases the surface area in contact.

• Sulfur dioxide – combines with water in the air to make sulfuric acid, causes acid rain.

• Nitrogen oxide – combines with water in the air to produce nitric acid, causing acid rain.

• Carbon dioxide – a byproduct of any burning, CO₂ is a greenhouse gas and is causing our Earth to warm excessively.

• Fly ash (very fine particulate) contains mercury and arsenic.  These toxins then settle into water systems where they become more concentrated.

1.  The energy required to make an electrical device operate is called the input energy. 

2.  The amount of useful work you get out of it is called output energy. 

3.  A transformer is used to change voltage from high to low, or from  low to high. 

     These are the green boxes you see in neighbourhoods.

4.  Power is the rate at which work is done.  The more power you have, the faster you

     can convert energy and do work.

5.  Power is measured in watts  (W), kilowatts  (kW) or megawatts  (MW).

6.  In households and businesses, meters are set to read kilowatt hours  which are a

     measure of how much power is consumed over a period of time.

7.  Energy is the ability to do work.

8.  Energy is measured  in joules (J),  kilojoules (kJ) or megajoules  (MJ).

9.  Energy efficiency  is the ratio between the useful output of an energy conversion device (heat, light,

     mechanical)  and the energy put into it.

10.  Incandescent bulbs use a resistant tungsten filament to produce light and are very inefficient because

      most of the electrical energy is converted to heat rather than light.

11.  Fluorescent bulbs use ionized gas to produce light and are somewhat more efficient at producing light.

12.  All appliances must have an Energuide label  to let consumers know how energy efficient it is compared to

      other models designed to do the same job.

13. The greatest cause of differences in energy efficiency is friction which produces wasted heat energy.

      The most efficient devices do what they can to reduce friction.

14.  Ball bearings  are smooth metal balls that are placed between pieces of metal that must move past each

      other.  This reduces friction.

15.  Renewable resources  are able to be replaced during a person’s  lifetime so that energy sources are

      available.

16.  Non-renewable resources  will take more than a generation to be replaced if ever.

17.  Biomass is carbon, hydrogen and oxygen based energy derived from garbage, wood,  waste, landfill gases

       and other plant material.

18.  Geothermal  energy comes heat deep within the Earth.  This heat is used to produce  stream for

       generators, or can be used to heat water in pipes.

19.  Fossil fuels are energy sources from ancient decayed plant material.  They include petroleum (oil), gas

      (natural, propane), and coal.

20.  An internal combustion engine is the standard type car engine that runs by burning gasoline.  

21.  Sulphur dioxide (SO₂) and nitrogen oxide (NO) are products of fossil fuel burning that lead to acid rain.

22.  Carbon dioxide (CO₂) is a product of fossil fuel burning that is the greenhouse gas  associated with an

        increase in the Earth’s temperature (global warming).

23.  Fly ash is a product of fossil fuel burning that is a dust containing dangerous chemicals such as arsenic.

24.  A resource is sustainable if it is used in a way that will allow the current generation to benefit, but

       ensures that the resource remains available to future generations.