Coulomb's Law (Electric Force) Practice Problems
The sun emits ions and electrons that travel through space. Consider 0.00100 kg of electrons that have just escaped from the sun and an equal amount of electrons that have arrived at Mars's surface (in practice reaching a planet's surface may be thwarted by the atmosphere and a planet's magnetic field). i) What is the net electric force that the two groups of electrons exert on each other? Take the two sets of electrons to be stationary and behave like a point charge. ii) Should gravitational force from the sun and Mars be included in computing net force on the electron groups? iii) Calculate the gravitational force the two sets of electrons exert on each other. Assume their position is equal to the radius of the sun and Mars respectively. Hint: Find electrons' separation from the orbital radius of Mars.
In an electrostatics virtual lab, small charged balls (can be approximated to point charges) are arranged as follows along the y-axis. Ball b1 is placed at the origin. and ball b2 at 3.00 cm. The charges of the balls are b1 = 2.00 μC, b2 = -4.00 μC, and b3 = - 6.00 μC. The net force on b1 is -5.00 N. What position of b3 results in that net force?
An electrostatics lab activity uses three charged spheres (that can be modeled as point charges) to study electric forces. Spheres s3 is placed at the origin, s2 at x = 4.00 cm, while s1 is placed at 8.00 cm. Spheres s3 and s1 have charges -4.00 nC and 6.00 nC, respectively. What is the magnitude and sign of the charge s2 if the net force from the other charges on s1 is zero?
Two glass balls are rubbed with silk to charge them positively. One ball has 5 times the charge on the other ball. When the balls are separated by 20.0 cm, the balls repel each other with a force of magnitude 0.280 N. Determine the charge on each sphere.
Two glass balls acquire an equal positive charge when charged by rubbing them with silk. When the balls are separated by 22.0 cm, the magnitude of the repulsive force between them is 0.320 N. Determine the charge on each sphere.
Two equally charged miniature steel ball bearings are positioned on insulating holders. The holders' separation is 16.0 cm. The balls repel each other with 5.0 × 10-19 N. Determine the number of extra electrons on each ball.
Two charged copper balls are 55.0 cm apart. The mass of each ball is 0.0200 kg. Electrons are transferred from one ball to the other until the spheres experience an attractive force of 7500 N. Express the transferred electrons as a fraction of the total electrons in one ball. Treat the charged balls like point charges.
Two decorative copper balls are 45.0 cm apart. Each ball has a mass of 0.0240 kg. Determine the number of electrons that should be transferred from one ball to the other to create an attractive force between the balls of magnitude 8000 N. Treat the charged balls like point charges.
A water droplet of mass m and charge q is placed between two parallel plates with a downward electric field. The droplet is negatively charged. When a certain potential difference is applied, it creates an electric field of strength E, keeping the droplet stationary. Find an equation for the droplet's charge q, given the electric field E and the droplet's weight mg.