Download 2.3 x 10 -8 N repulsion

Coulomb's Law Practice problems: Show G-U-E-S-S in the space provided.
k = 8.99 x 109 N·m2/C2
1. What is the electrostatic force between two metal spheres, each having 5 C of charge. The balloons
are 0.30 m apart.
2.5 x 1012 N
2. Suppose that two point charges, each with a charge of +1 Coulomb are separated by a distance of
1 meter. (a) Will they attract or repel? (b) Determine the magnitude of the electrical force between them.
9 x 109 N
3. Two balloons are charged with an identical quantity and type of charge: -0.0025 C. They are held
apart at a separation distance of 8 m. Determine the magnitude of the electrical force of repulsion
between them.
878.9 N
4. Two charged boxes are 4 meters apart from each other. The blue box has a charge of +0.000337 C
and is attracting the red box with a force of 626 Newtons. Determine charge of the red box. Remember
to indicate if it is positive or negative.
0.0033 C
5. A piece of styrofoam has a charge of -0.004 C and is placed 3 m from a piece of salt with a charge of
-0.003 C. How much electrostatic force is produced?
12,000 N
6. A helium nucleus has charge +2e and a neon nucleus +10e, where e = 1.60 x 10-19 coul. With what
force do they repel each other when separated by 3 x 10-9 meters?
5.1 x 10-10 N
7. If two equal charges, each of 1 coulomb, were separated in air by a distance of 1 km, what would be
the force between them?
9000 N repulsion
8. Determine the force between two free electrons spaced 1 angstrom (10-10 m) apart.
2.3 x 10-8 N repulsion
9. The force of repulsion between two argon nuclei is 7.4 x 10-8 N when separated by what distance.
The charge on an argon nucleus is +18e.
1.004 x 10-9 m
10. Two equally charged pith balls are 3 cm apart in air and repel each other with a force of 4 x 10-5 N.
Compute the charge on each ball.
2 x 10-9 C
11. Two small equal pith balls are 3 cm apart in air and carry charges of +3 x 10-9 and
–12 x 10-9 C respectively. Compute the force of attraction.
If the balls are touched and then separated by a distance of 3 cm, what will be the force between
them? (hint: the charge of each pith ball will be the average of the two charges).
a) 3.6 x 10 –4 N
b) 2 x 10-4 N repulsion
Electrical Notes
1. Like charges ___repel_____, opposites ____attract______.
2. Describe an insulator and give examples:
Does not conduct heat and electricity very well. Cotton, air, glass, etc.
3. Describe a conductor and give examples:
Allows heat and electricity to move through the substance easily. Metals, saltwater, etc.
4. Charge of an electron: -1.6 x 10-19C
Charge of a proton: +1.6 x 10-19C
Same number, opposite sign
5. What is Coulombs Law? (explain each letter)
F=kqq/r2 F is force (N), k is Coulombs constant (8.99 x 109Nm2/C2), q is the charge (C), r is
the distance between the charges (m).
6. Draw an electric field around a positive charge:
7. Draw an electric field around a negative charge:
8.