Answer:
Charge enter a 0.100 mm length of the axon is

Step-by-step explanation:
Electric field E at a point due to a point charge is given by

where
is the constant =

is the magnitude of point charge and
is the distance from the point charge
Charges entering one meter of axon is

Charges entering 0.100 mm of axon is

substituting the value of
in above equation, we get charge enter a 0.100 mm length of the axon is
