Static Electricity – Electric Field

The electric field strength (

E

) is defined as the amount of force exerted upon a test charge per unit of charge on the test charge (

q

). That is, 

E = F / q

.

The electric force (

F

) depends upon a number of variables as described by Coulomb’s law: 

Felect= k • Q1• Q2/ d2

 
In the above equation, 

 might be the source charge 

 and 

 might be the test charge 

q

. If the expression for force as given by the Coulomb’s law equation is substituted in for 

 in the electric field strength equation, then the equation for electric field becomes

​E = k • Q / d2