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OP48 use simple materials to generate static electricity; demonstrate the force between charged objects and the effect of earthing
use simple materials to generate static electricity
these demonstrations are best done in dry weather.
take a ferrero roche box,
rip up some light tissue/crepe paper into TINY pieces
putting the tissue in the box.
rub the top of the box with a clean dry cloth, and observe.
Demonstration
In a dark room on a dry day, allow 3 mins for your eyes to adapt to the low light conditions
- Peel some sellotape off a surface
- Get some sugar and crush it using a clear plastic ruler or similiar
- Take off a school jumper
Rub a blown up balloon on your jumper , hold it near a cloth curtain ..... or a wall .....
Rub a plastic biro in your hair or on your jumper, hold this charged pen close to a
slowly running tap ...... or small bits of paper
Run your comb through your hair a number of times this to becomes a charged body
You are producing an electrostatic force
? does this electrostatic force appear in all objects ?
can you charge a thin strip of aluminium (tin foil),
rub the foil and see if you can get it to cling on to a wall or a balloon ?
Pour out some salt and pepper in a pile,
Ask the students if the can separate the salt from the pepper?
Charge a plastic spoon
Homework
Describe 3 ways of demonstrating Static electricity!!
Use diagrams please !
demonstrate the force between charged objects
Like Charges Repel, Opposite Charges Attract
If one material takes a + charge, the other sur+_++face it is rubbed off take a - charge !!!
Polythene bag strips ....
get some plastic shopping bags.
cut into strips, give 2 strips to each student (student group of 2)
Place a strip on the desk,
Hold it down with one hand
and using the side of your other hand rub the plastic bag strip a number of times
Do it again to the other strip (or have your lab partner do it)
Bring the 2 strips towards each other.
Observe, what happens ?
bring your hand towards the plastic bag strip
Observe, what happens ?
To Demonstrate different bodies have a different charge
3 rods, Perspex, Glass and Polythene, a paper cradle, cloth, retort stand
- Place 1 rod in the cradle suspend it from the retort stand
- Charge this rod up
- Charge up another rod bring it towards the rod in the cradle
- observe any movement in terms of attraction or repulsion
- charge up the other rod and do the same.
- change rods and repeat to fill the table
Similiarly charged objects repel
Differently charged objects attract
The only objects that we can get a charge on are called Insulator, they gather charge on their outsides. The oppositie of an Insulator is a Conductor. This allow electricity to flow through them and so do not keep it on the outside!
What are you doing in these demonstrations is stripping a material that easily gives away electrons, of its electrons where they transfer to a material that likes to hold on to electrons. Electrons are tiny, and compared to their size they have a very large electrostatic force (the ability to attract or repel). A
How do I make this electrostatic force ?
Rub an object against another object,
What happens when we rub an object off another,
it strips electrons from one object and transfers it to another object.
One object will have more ______ and one object will have less ______
Bodies become charged by the loss or gain of _______________.
They say an electron has a negative charge, and a proton has a positive charge.
A body is __Negativly___ charged if it
gains electrons.
A body is ___Positively___ charged if it loses electrons.
Some materials give up their electrons easily, naturally positive materials
some materials gain electrons easily, these materials can be considered naturally negative materials
When static electricity builds up on an object you can get an electric shock if you touch it.
the effect of earthing
Lightning is a form of shock. Electricity passes across the atmosphere from the clouds to the ground. Static Electricity builds up in materials that cannot pass on their excess charge .... the extra electrons (or the lack of electrons). This object is said to be 'grounded' when the excess of charge is reset / balanced. This is easiest done by contact between the object and the earth.
When we say we are earthing something, we could say we are allowing the charge to pass from the surplus charge to earth, no charge.
The 1st form of electricity that was known to people was just Lightning. Lightning was thought to be the work of supernatural forces. Many European Christians at the time of Franklin believed it to be diabolical in origin, based largely on the interpretation of a single phrase in the Bible. .....
Ephesians 2: 2 (KJV)
Wherein in time past ye walked according to the course of this world,
according to the prince of the power of the air,
the spirit that now worketh in the children of disobedience:
The Power of lightning as described by the destruction of church bell towers.
Short quote from White.
robbed wholesale from physics.info/charge/
As late as 1770 religious scruples regarding lightning-rods were still felt, the theory being that, as thunder and lightning were tokens of the Divine displeasure, it was impiety to prevent their doing their full work.
Fortunately, Prof. John Winthrop, of Harvard, he declared, "It is as much our duty to secure ourselves against the effects of lightning as against those of rain, snow, and wind by the means God has put into our hands."
As late as 1783 it was declared in Germany, on excellent authority, that within a space of thirty-three years after Franklin discovered the lightning conductor nearly four hundred towers had been damaged and one hundred and twenty bell-ringers killed.
In Roman Catholic countries a similar prejudice was shown, and its cost at times was heavy. In Austria, the church of Rosenberg, in the mountains of Carinthia, was struck so frequently and with such loss of life that the peasants feared at last to attend service. Three times was the spire rebuilt, and it was not until 1778 - twenty-six years after Franklin's discovery - that the authorities permitted a rod to be attached. Then all trouble ceased.
A typical case in Italy was that of the tower of St. Mark's, at Venice. In spite of the angel at its summit and the bells consecrated to ward off the powers of the air, and the relics in the cathedral hard by, and the processions in the adjacent square, the tower was frequently injured and even ruined by lightning. In 1388 it was badly shattered; in 1417, and again in 1489, the wooden spire surmounting it was utterly consumed; it was again greatly injured in 1548, 1565, 1653, and in 1745 was struck so powerfully that the whole tower, which had been rebuilt of stone and brick, was shattered in thirty-seven places. Although the invention of Franklin had been introduced into Italy by the physicist Beccaria, the tower of St. Mark's still went unprotected, and was again badly struck in 1761 and 1762; and not until 1766 - fourteen years after Franklin's discovery - was a lightning-rod placed upon it; and it has never been struck since.
The Republic of Venice had stored in the vaults of this church over two hundred thousand pounds of powder. In 1767, seventeen years after Franklin's discovery, no rod having been placed upon it, it was struck by lightning, the powder in the vaults was exploded, one sixth of the entire city destroyed, and over three thousand lives were lost.
Range of conductors should vary in their ability to conduct.
Van de graff
Hold a van de graff generator and touch off the gas flow!
van de graff @
Uses of Static electricity
2 of the most important applications of Electric fields are in the following link. They are important and cool but are quite advanced for Junior Science, they are on the leaving cert. Oh and they are Photocopying and removal of smoke particles from Chimneys. bbc.co.uk//bitesize/sci//elect/staticelectrev2.shtml
All charge wants to get to the earth, sometime (when the > 2kV) we will feel this electricity passing through us as a shock. It is when this charge is prevented nor not easily allowed to pass to earth we get the shocks and destruction such as lightning.
Electrical circuit. Steel Wool. Variable resistance. Bulb.
Use circuit as above.
Vary resistance
Record current.
Tabulate
Ben Franklin: The Plus and Minus.
One pioneering researcher, Benjamin Franklin, came to the conclusion that there was only one fluid exchanged between rubbed objects, and that the two different "charges" were nothing more than either an excess or a deficiency of that one fluid. After experimenting with wax and wool, Franklin suggested that the coarse wool removed some of this invisible fluid from the smooth wax, causing an excess of fluid on the wool and a deficiency of fluid on the wax. The resulting disparity in fluid content between the wool and wax would then cause an attractive force, as the fluid tried to regain its former balance between the two materials.
Postulating the existence of a single "fluid" that was either gained or lost through rubbing accounted best for the observed behavior: that all these materials fell neatly into one of two categories when rubbed, and most importantly, that the two active materials rubbed against each other always fell into opposing categories as evidenced by their invariable attraction to one another. In other words, there was never a time where two materials rubbed against each other both became either positive or negative.
Following Franklin's speculation of the wool rubbing something off of the wax, the type of charge that was associated with rubbed wax became known as "negative" (because it was supposed to have a deficiency of fluid) while the type of charge associated with the rubbing wool became known as "positive" (because it was supposed to have an excess of fluid). Little did he know that his innocent conjecture would cause much confusion for students of electricity in the future!
from http://www.allaboutcircuits.com/vol_1/chpt_1/1.html
From The First American: The Life and Times of Benjamin Franklin,
by H.W. Brands,
here is a description of Franklin's ongoing correspondence begun in 1747 with Peter Collinson in London. Collinson was an agent of the Library Society of Philadelphia, and a scholar with
scientific interests similar to Franklin's:
"In one of his first letters, Franklin supplied a novel terminology that became standard in analyzing electrical phenomena. Describing a particular apparatus, consisting of bodies labeled A and B, he wrote: 'We say B (and other bodies alike circumscribed) are electrised positively; A negatively. Or rather B is electrised plus and A minus ….' At a time when other electricians spoke of two different kinds of electricity — vitreous and resinous — Franklin unified the field by positing a single sort and explaining the opposite properties in terms of a surfeit or a deficit (that is, positive condition or negative) of this single electricity, with uncharged objects being in balance."
Crocs, the fashionable plastic clogs, could be banned from all hospitals because it is feared they interfere with life-saving medical equipment.
The soles on the shoes are thought to generate static electricity which is strong enough to knock out respirators and machines in operating theatres.
The comfy footwear has become hugely popular over the past few years and are a particular favourite with nurses as they enable them to endure long hours on their feet.
But they are now expected to be banned from the Sheffield Teaching Hospitals NHS trust in South Yorks, and other hospitals are set to follow suit.
Make a miniture Battery
10 x 2p pieces, tinfoil , blotting paper, copperwire, vinegar, salt, bowl, LED, Masking tape
- mix the vinegar & salt (the vinegar is the electrolyte, salt will form the ions)
- soak circles of the blotting paper in the solution
- using masking tape attact the copper wire to one of the aluminium disk
- now stack foil, paper, coin, foil, paper, coin .....
- join another wire joined to the 1st wire through the LED to the final coin using the tape again
More Importantly The Resistors talk about Electricity
http://www.theresistors.com/electric1a.htm
click on the Voltaic piles, and press PLAY
To avoid shocks when getting out of the car -
HOLD the metal door frame before you get out
KEEP HOLDING as you get out, until you are fully out of the car.
It's easy with practice!
For an indepth description of how lightning is caused follow the link below. Basic at the beginning, and featuring diagrams.
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/lightning.html#c1
Electric Shock
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/shock.html#c1
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