Static electricity

static electricity
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NatuurkundeMiddelbare schoolhavo, vwoLeerjaar 2,3

This lesson contains 33 slides, with text slides and 10 videos.

time-iconLesson duration is: 50 min

Items in this lesson

static electricity

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You can explain the flow of electric current
You can explain what causes static electricity
You can explain why static electricity could be very dangerous

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Rub your pen against your sweater.
Then try if you can pick up some paper snippets.

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Rub a dry plastic comb through your hair for about ten times.
Of course your hair needs to be dry as well otherwise it would behave as a conductor

Then place the comb near a very narrow stream of water.
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You can change some variables to experiment:
  1. the temperature
  2. a bigger comb
  3. the material of the comb
  4. the strength of the waterflow
2

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Static electricity
Static electricity is a build up of electric charge on insulated materials. This cause sparks when discharged.

Normally all materials are neutrally charged meaning that all positive and negative charges cancel each other out.

Because of friction this situation may change.

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When two objects are rubbed together, the friction causes electrons from one object to move to another.

This causes one of the objects to become positive, while the other becomes negative. 

This only works with insulating materials since the electrons would flow right back if you use a conducting material.
As you can see in the picture the way the electrons move from one object to another depends ooon which type of materials are rubbed together!
!

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And when you have changed the net charge in an object, 
you can use that very object to influence it surroundings

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Because of the friction between two objects and the movement of the electrons, you will get a charge buildup eventually which can cause a potential difference.

This may result in an electric shock which could be very dangerous like on the case of fueling an airplane or lightning for instance.
Potential difference

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Lightning?
It is very dangerous and deadly

and think about what if it was you.. what would you have done?

to prevent this?

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Building blocks
Materials are made out of tiny molecules and atoms. 
When you look deep down into an atom you will 
discover that it is made out of protons (+), neutrons
and electrons (-). 

Normally most substances are neutrally charged, 
meaning that you have an equal amount of positive
and negative charged particles.

Under certain circumstances the negative particles 
can move around causing a change in the overal charge.
nucleus

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Conductivity
In some materials some of the electrons experience less 
attraction by the positive charge in the atom's nucleus.

Because of this, they have a chance to move around.
This can be caused by simply rubbing the material, but
also by connecting it in an electrical circuit.

From now on we call moving electrons electric current.
Although electrons (-)  flow towards a positive (+) charged 
objects, it is agreed upon that when we talk about 
electric current the current flows from + to -
Insulator
conductor

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Electric current
Electric current is caused by the movement of electrons 
(electric charge) from one place to another. The electrons 
carry energy which they can give away where needed. 

After transferring their energy they will continue on their
way to the other side of the battery (or powersource). The
electrons themselves are not used. You can compare them
with a shopping cart which is returned after transferring 
your groceries to your car.


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