Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
Useful Words To Remember
Battery – an electrical energy source
Bulb – a light source powered by electricity
Buzzer – a sound source powered by electricity
Motor – a device that uses electricity to produce movement
Break – in an electric circuit a break will stop the circuit working
Electrical Insulator – a material that will not allow electricity to pass through it
Electrical Conductor - a material that will allow electricity to pass through it
Metal – a good conductor of electricity
Plastic – an electrical insulator
What Is A Circuit?
A circuit is an electrical device that provides a path for electrical current to flow.
What Is A Conductor?
A conductor can be either:
A device designed to transmit electricity, heat, etc.- A substance that readily conducts e.g. electricity and heat.
Conductors are materials in which it is easy to get electrons to move and provide a flow of electric current. Conductors are mostly metals such as gold, silver, copper, iron and lead. Carbon is a conductor as well as some gases (as in fluorescent tubes) and water containing some chemicals. These are not perfect conductors and offer some resistance to the flow of current.
The resistance of a conductor (such as a metal rod) is determined by three things:
- Its length. The longer its length the higher its resistance.
- Its cross-sectional area. The bigger this is the lower is its resistance.
- The material of which it is made.
All materials have RESISTIVITY. The higher the value of resistivity the higher the resistance. It is measured in OHM METERS.
length x resistivity
Resistance = -------------------------------
cross-sectional area
What Is An Electrical Current?
An electric current is a flow of microscopic particles called ELECTRONS flowing through wires and electronic components. It can be likened to the flow of water through pipes and radiators, etc.
As water is pushed through pipes by a pump, electric current is pushed through wires by a battery. Hot water does work by heating radiators. Electric current does work by heating fires, lighting lamps, ringing bells, electroplating, etc. A basic law of the universe is that like charges repel and unlike attract. Two negatives will repel each other. A negative and a positive will attract each other.
An electron has a negative charge. The negative (-ve) terminal of a battery will push negative electrons along a wire. The positive (+ve) terminal of a battery will attract negative electrons along a wire. Electric current will therefore flow from the -ve terminal of a battery, through the lamp, to the positive terminal.
Conductivity Experiment
Listed below are a number of objects, try to find out which objects conduct electricity and which don’t!! Record your results!!
A comb
A piece of fabric
Metal spoon
A one pence piece- A rock
Batteries
Batteries are assembled from cells, connected in series, to increase the voltage available. In a cell, chemical energy is converted into electrical energy. Cells may be either PRIMARY or SECONDARY types.
A primary cell is discarded when its chemical energy is exhausted. A secondary cell can be recharged. The most common primary cell is the
zinc/carbon as used in
torches,
portable radios etc.
Build Your Own Battery
Remember get an adult to help you with this!!!
The Problem:
Frankenstein's lab is running out of electricity and you have been asked to help find a temporary source of energy to get a single light for the doctor.
Can you help? Yes you can, because there in the lab is a bowl of fruit!! Did you know that fruit can make electricity?
What Will You Need?
-
Citrus fruit (lemons or limes work best)
- 1 copper screw about 5 cm long
- 1 zinc screw about 5 cm long
- 1 small light with 5 cm of wire attached
What Do You Need To Do?
You already know that a battery is nothing more that a device that stores metals and chemicals.
Lemons, limes contain acids so perhaps they will help you!!
What You Need To Do
-
Roll the fruit under the palm of your hand to soften it, be careful you don't break the skin. Work it gently on a piece of scrap paper or a paper towel.
- Insert the screws into the fruit about 5 cm apart. Don't allow the screws to go through the bottom skin of the fruit.
- Carefully remove about 1 cm of the insulation from the lead on the light. Do not cut into the wire beneath the insulation!!!
- Twist one end of the wire around one screw and the other end around the other screw. What do you get> You should now have a light!!!
Some Cool Links
Click on any of the links below to find out lots of more cool stuff about circuits, conductors & electricity.
Have fun!!!
Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
