There are other forms of energy but electricity is tody one of the most importants. We need electricity to charge our mobile phones, our computer or to switch on the lights at home. We plug our devices and they start to work but, how is electricity produced?
Maybe this video will help us:
1.2 DISCUSS
Let's try to find some answers after watching the video for the first time:
Do you think electricity can be transformed in other kinds of energy?
Is electricity a clean energy? Why?
1.3 EXERCISE
Watch the video for the second time and answer the following true or false questions:
We get electricity by changing other forms of energy. T/F
We can burn coal or some other fuel which changes kinetic energy into thermal. T/F
The electric energy will cause water to heat and move in a tank. T/F
Energy of motion is kinetic energy. T/F
Generator turns the turbine. T/F
Generator changes kinetic energy to electrical energy. T/F
2. CONDUCTORS AND INSULATORS: Simple circuits.
2.1 DEFINITION
CONDUCTORS: Materials that let elecricity pass through them easily are known as electric conductors.
INSULATORS: Materials that do not allow electricity to pass through them ara known as electric insulators.
2.2 EXERCISE
Check the following table and indicate which materials are conductors or insulators:
MATERIAL
CONDUCTOR
INSULATOR
IRON
GLASS
WOOD
CUPPER
STEEL
RUBBER
PLASTIC
ALUMINIUM
PAPER
2.3 DISCUSS
Discuss in pairs the following questions. After that, you will explain your conclusion to your classmates.
- Why are cables covered with plastic?
- Do you think you are an electric conductor or an insulator?
- Is it dangerous to manipulate electric devices? What precautions would you recommend?
- Was the video difficult to understand?
2.4 BASIC CIRCUITS
Watch the following video about basic circuits and some conductors and insulators tips.
Try to understand as much as you can.
After watching the video for the firs time, answer the following questions.
- Do electrons flow from the positive side of the battery?
- What is a complete circuit?
- What happens when electrons take a path short of the complete circuit?
Now watch the video again and following the video translation below. Were your answers right? Why?
Then, look up in the multidict the specialised terms you find and make a little glossary with them.
0:08 Let's begin by looking at how a simple circuit
0:11 allows a light bulb to light.
0:14 A circuit is a route through which electrical current can flow.
0:18 In our example,
0:20 electrons flow from the negative side of a D-cell battery
0:24 to a conducting material on the base of the bulb.
0:28 From there,
0:29 the electrons flow up a wire that is inside the bulb
0:32 and across the filament,
0:34 which is the part of the bulb that actually lights.
0:37 When the electrons go through the filament,
0:40 some of the electrical energy is changed to heat and light energy.
0:46 The electrons continue down another small wire inside the bulb
0:50 to another conductor on the base of the bulb.
0:53 The electrons finally make their way to
0:56 the positive side of the battery.
0:58 There would not be a complete circuit if the electrons did not travel
1:02 to the positive side of the battery,
1:04 and the bulb would not light.
1:07 When there is an unbroken path on which electrons flow,
1:11 as in this example, it is called a complete circuit.
1:15 The unbroken path that the electrons follow
1:18 is called a closed circuit.
1:20 Because electricity will only flow on an unbroken path,
1:25 the light bulb will not light unless there is a closed circuit.
1:30 Now look closely at the light bulb
1:32 and you'll notice that there is an insulator between the conductor
1:36 that leads up to the filament and the conductor
1:39 that leads away from the filament.
1:42 Remember that the atoms of conductors
1:44 easily accept and pass on electrons;
1:47 the atoms of insulators do not.
1:50 As we discussed in the first section of the lesson,
1:53 electrons will not easily pass through insulating material
1:56 that surrounds a wire.
1:58 If an insulator did not surround a wire carrying a current,
2:02 it is possible for the electron flow
2:04 to get directed to another conductor
2:07 that comes into contact with the circuit.
2:11 Electricity will follow the path of least resistance.
2:14 If the electrons take a path short of the complete circuit,
