The force F is then negligibly small but the
ratio F/q is finite and defines the electric field:
E
F
=


→
qlim
q
0
(1 9)
A practical way to get around the problem (of keeping Q undisturbed
in the presence of q) is to hold Q to its location by unspecified forces This may look strange but actually this is what happens in practice When we are considering the electric force on a test charge q due to a
charged planar sheet (Section 1