Electric Force Worksheet #1
k = 8.99 x 109 N·m2/C2
Elementary Charge = ±1.6 x 10-19 C
Be careful with your metric prefixes!! (remember:
1. Two charges, qA and qB are separated by a distance d. As a result, they exert a force, F,
on each other. What new force will exist, in terms of F, in the following situations:
a) qA is doubled.
b) qA and qB are both cut in half.
c) d is tripled.
d) d is cut in half.
e) qB is tripled and d is cut in half.
2. An ion is an atom or molecule (atoms stuck together!) whose charge is unbalanced.
For example, a sodium ion in salt water has 11 protons and 12 electrons. What is the
net charge of ionized sodium? (This can be made very easy if you think a bit before
calculating… in fact you don’t really need to calculate!)
5. Two electrons in an atom are separated by 1.5 x 10-11 meters; the typical size of an
atom. What is the electrical force between them? Is this an attraction or a repulsion?
6. A repelling force of 4400 Newtons exists between a charge of –8.0 x 10-4 C and a
charge of –3.0 x 10-4 C. What is the distance between them?