Current and Potential Difference

3.1  Current and Potential Difference
 
  Electric field  
  The region around a charged particle where any electric charge in the region will experience an electric force  
     
 
 

The patterns of observed electric fields for positive charge and negative charge are as follows:

(a)

The direction of the electric force line avoids the positive charge.

   
(b)

The direction of the electric force line to negative charge.

   
 
 
  Electric field strength, E  
 

Electric force acting on a unit positive charge placed at the point.

 
     
  \(E=\dfrac{F}{q}\), where E = electric field strength, F = electric force, Q = quantity of electric charge  
     
 

 \(E=\dfrac{V}{d}\), where E = electric field strength, V = potential difference, d = distance between plates

 
     
 
 
  Electric current, \(I\)  
  Rate of flow of charge in a conductor  
     
  \(I = \dfrac{Q}{t}\)\(I\) = current, Q = total charge, t = time  
     
 
 
  Potential difference  
  Work done in moving one coulomb of charge from one point to another.  
     
  \(V = \dfrac{W}{Q}\) or \(V=\dfrac{E}{Q}\), where V= potential difference, W = work done,  E = energy transferred, Q = amount of charges flowing