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In a salt crystal, the distance between adjacent sodium and chloride ions is What is the force of attraction between the two singly charged ions?
Protons in an atomic nucleus are typically apart. What is the electric force of repulsion between nuclear protons?
Suppose Earth and the Moon each carried a net negative charge − Q . Approximate both bodies as point masses and point charges.
(a) What value of Q is required to balance the gravitational attraction between Earth and the Moon?
(b) Does the distance between Earth and the Moon affect your answer? Explain.
(c) How many electrons would be needed to produce this charge?
Point charges and are placed 1.0 m apart. What is the force on a third charge placed midway between and ?
Where must of the preceding problem be placed so that the net force on it is zero?
Two small balls, each of mass 5.0 g, are attached to silk threads 50 cm long, which are in turn tied to the same point on the ceiling, as shown below. When the balls are given the same charge Q , the threads hang at to the vertical, as shown below. What is the magnitude of Q ? What are the signs of the two charges?
The tension is
. The horizontal component of the tension is
.
The charges can be positive or negative, but both have to be the same sign.
Point charges and are located at and . What is the force of on ?
The net excess charge on two small spheres (small enough to be treated as point charges) is Q . Show that the force of repulsion between the spheres is greatest when each sphere has an excess charge Q /2. Assume that the distance between the spheres is so large compared with their radii that the spheres can be treated as point charges.
Let the charge on one of the spheres be rQ , where r is a fraction between 0 and 1. In the numerator of Coulomb’s law, the term involving the charges is This is equal to . Finding the maximum of this term gives
Two small, identical conducting spheres repel each other with a force of 0.050 N when they are 0.25 m apart. After a conducting wire is connected between the spheres and then removed, they repel each other with a force of 0.060 N. What is the original charge on each sphere?
A charge is placed at the point P shown below. What is the force on q ?
Define right to be the positive direction and hence left is the negative direction, then
What is the net electric force on the charge located at the lower right-hand corner of the triangle shown here?
Two fixed particles, each of charge are 24 cm apart. What force do they exert on a third particle of charge that is 13 cm from each of them?
The particles form triangle of sides 13, 13, and 24 cm. The
x -components cancel, whereas there is a contribution to the
y -component from both charges 24 cm apart. The
y -axis passing through the third charge bisects the 24-cm line, creating two right triangles of sides 5, 12, and 13 cm.
in the negative
y -direction since the force is attractive. The net force from both charges is
.
The charges and are placed at the corners of the triangle shown below. What is the force on
What is the force on the charge q at the lower-right-hand corner of the square shown here?
The diagonal is
and the components of the force due to the diagonal charge has a factor
;
Point charges and are fixed at and What is the force of ?
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