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Rev. Notes > IGCSE > Elecrical Quantities
 
 
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Electric charge

One Coulomb Charge Production of electric charge
Detection of electric charge Experiment to detect the electric charge Electrical conductors and insulators
Electric field Electrostatic forces Application of electrostatic forces
Electric current One Ampere of electric current Direction of electric current
Basic relation of electric current Direct current Alternating current
Ammeter Electromotive force - (e.m.f.) Potential difference
One Volt Explanation of potential difference Measurement of potential difference
Voltmeter Resistance Affect of length of the conductor on resistance
Affect of cross-sectional area on resistance Affect of temeprature on resistance How nature of material affects the eresistance
Ohm's law Potential difference - Current graph for Ohmic conductors Potential difference - Current graph for tungsten filament
Potential difference - Current graph for semiconductor diode Electrical energy Formula for electrical energy
Electrical Power Formulae for electrical power
 

Production of electric charge

When you charge an object you are giving or taking away negatively charged electrons, so that the charge on the object overall is unbalanced. For example, when you rub a glass or acetate rod with a cloth, elecrons from the rod get rubbed on to the cloth. So the cloth become negatively charged overall and the rod is left with an overall positive charge. When you rub a polythene rod with a cloth, electrons from the cloth get transferred to the rod, so the polythene carries a negative charge overall, and the cloth carries a positive charge.

Material like glass, acetate and polythene can only become charged because they are insulators. Electrons donot move easily through insulating materials so when extra electrons are added, they stay on the surface instead of flowing away and the surface stays negatively charged. Simmilarly if electrons are removed, electrons from other part of material do not flow in to replace them, so the surface stays positively charged. A material through which electrons flow easily is called a conductor. Conductors, such as metal can not be charged by rubbing.

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View Comments on this Chapter - Total Comments (6)
 
sree Said :
wish these had a diagrams
 
  24/12/15 10:01 AM
   
student 567 Said :
There are no diagrams, but seeing that you don't give a shit... why should i bother to comment?! Can you just put the dam diagram up already!
 
  18/04/14 08:10 PM
   
Deepak varun Said :
there is a spelling mistake to say said they said asaid please change it admin
 
  17/11/13 06:26 AM
   
gargi sachdev Said :
diagrams aren't there ...
 
  29/08/12 12:35 AM
   
gargi sachdev Said :
diagrams aren't there ...
 
  29/08/12 12:35 AM
   
Ajay Said :
I cant see any diagrams? can u help me with it
------------------------------------------------------------------------------------- Admin Replied:

Hi Ajay, thank you for informing us about this issue. We will make sure we make those images available for you as soon as possible.

Thank you

 
  15/03/12 12:13 PM
 

 

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