24. Electric Force & Field; Gauss' Law

Coulomb's Law (Electric Force)

Open Question
Just How Strong Is the Electric Force? Suppose you had two small boxes, each containing 1.0 g of protons. (a) If one were placed on the moon by an astronaut and the other were left on the earth, and if they were connected by a very light (and very long!) string, what would be the tension in the string? Express your answer in newtons and in pounds. Do you need to take into account the gravitational forces of the earth and moon on the protons? Why? (b) What gravitational force would each box of protons exert on the other box?
Open Question
What is the force F on the 1.0 nC charge in FIGURE EX22.20? Give your answer as a magnitude and a direction.
Multiple Choice
If the force between two charges is F when the distance is d, what will the force between the two charges be if they were moved to a distance of 2d?
Multiple Choice
In which direction will the −1 C charge move? If it has a mass of 10 g, what will its initial acceleration be?
Multiple Choice
What is the direction of the net force on the charge at the center of the square in the following figure?
Multiple Choice
What is the distance between a $10 μ C$ charge and a $24 μ C$ charge if the magnitude of the force between them is $1.2 mN$ ?
Multiple Choice
There is a $- 4.00 nC$ charge at the origin. A $9.00 nC$ charge is on the x-axis at $x = 2.00 m$ . A $5.00 nC$ charge is on the y-axis at $y = - 1.00 m$ . What is the total force on the $- 4.00 nC$ charge at the origin? Give your answer as a magnitude and an angle counterclockwise from the positive x-axis.
Multiple Choice
What is the relationship between the gravitational force between two electrons, $F_{G}$ . and the electric force between two electrons, $F_{E}$ ?
Multiple Choice
A $3.0 nC$ charge is at the origin, a $- 12 nC$ charge is at $x = 2.0 cm$ . Where, on the x-axis, could you place a $- 45 nC$ charge so that it would experience no net force?
Open Question
Three point charges are arranged along the x-axis. Charge q1 = +3.00 mC is at the origin, and charge q2 = -5.00 mC is at x = 0.200 m. Charge q3 = -8.00 mC. Where is q3 located if the net force on q1 is 7.00 N in the -x-direction?
Open Question
Three point charges are arranged on a line. Charge q3 = +5.00 nC and is at the origin. Charge q2 = -3.00 nC and is at x = +4.00 cm. Charge q1 is at x = +2.00 cm. What is q1 (magnitude and sign) if the net force on q3 is zero?
Open Question
Two small plastic spheres are given positive electric charges. When they are 15.0 cm apart, the repulsive force between them has magnitude 0.220 N. What is the charge on each sphere (b) if one sphere has four times the charge of the other?
Open Question
Two small plastic spheres are given positive electric charges. When they are 15.0 cm apart, the repulsive force between them has magnitude 0.220 N. What is the charge on each sphere (a) if the two charges are equal and
Open Question
Two small spheres spaced 20.0 cm apart have equal charge. How many excess electrons must be present on each sphere if the magnitude of the force of repulsion between them is 3.33 * 10^-21 N?
Open Question
Two small aluminum spheres, each having mass 0.0250 kg, are separated by 80.0 cm. (c) What fraction of all the electrons in each sphere does this represent?