Your roommate is having trouble understanding why solids form. He asks, “Why would atoms bond into solids rather than just floating freely with respect to each other?” To help him understand at least one type of bonding in solids, you decide to embark on an energy explanation. You show him a drawing of a primitive cell of a sodium chloride crystal, NaCl, or simple table salt. The drawing is shown in Figure P24.10, where the orange spheres are Na+ ions and the blue spheres are Cl− ions. Each ion has a charge of magnitude equal to the elementary charge e. The ions lie on the comers of a cube of side d. You explain to your roommate that the electrical potential energy is defined as zero when all eight charges are infinitely far apart from each other. Then you bring them together to form the crystal structure shown. (a) Evaluate the electric potential energy of the crystal as shown and (b) show that it is energetically favorable for such crystals to form.
Figure P24.10
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Chapter 24 Solutions
Physics for Scientists and Engineers
- Often we have distributions of charge for which integrating to find the electric field may not be possible in practice. In such cases, we may be able to get a good approximate solution by dividing the distribution into small but finite particles and taking the vector sum of the contributions of each. To see how this might work, consider a very thin rod of length L = 16 cm with uniform linear charge density = 50.0 nC/m. Estimate the magnitude of the electric field at a point P a distance d = 8.0 cm from the end of the rod by dividing it into n segments of equal length as illustrated in Figure P24.21 for n = 4. Treat each segment as a particle whose distance from point P is measured from its center. Find estimates of EP for n = 1, 2, 4, and 8 segments. FIGURE P24.21arrow_forwardAn old model of a hydrogen atom has the charge +e of the proton uniformly distributed over a sphere of radius a0, with the electron of charge -e and mass m at its center. (a) What would then be the force on the electron if it were displaced from the center by a distance r # a0? (b) What would be the angular frequency of oscillation of the electron about the center of the atom once the electron was released?arrow_forward(a) Find the mass density of a proton, modeling it as a solid sphere of radius 1.00 x 10-15 m. (b) What If? Consider a classical model of an electron as a uniform solid sphere with the same density as the proton. Find its radius. (c) Imagine that this electron possesses spin angular momentum Iω = h/2 because of classical rotation about the z axis. Determine the speed of a point on the equator of the electron. (d) State how this speed compares with the speed of light.arrow_forward
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- A solid plastic sphere of radius R1 = 8.00 cm is concentric with an aluminum spherical shell with inner radius R2 = 14.0 cm and outer radius R3 = 17.0 cm (Fig. P25.67). Electric field measurements are made at two points: At a radial distance of 34.0 cm from the center, the electric field has magnitude 1.70 103 N/C and is directed radially outward, and at a radial distance of 12.0 cm from the center, the electric field has magnitude 9.10 104 N/C and is directed radially inward. What are the net charges on a. the plastic sphere and b. the aluminum spherical shell? c. What are the charges on the inner and outer surfaces of the aluminum spherical shell? FIGURE P25.67arrow_forwardA solid sphere of radius R has a spherically symmetrical, nonuniform volume charge density given by (r) = A/r, where r is the radial distance from the center of the sphere in meters, and A is a constant such that the density has dimensions of M/L3. Sketch a graph of the magnitude of the electric field as a function of distance for 0 r 3R.arrow_forwardWhich word or name has the same symmetry as the letters in the name ZAK? (Explain your answer.) a. NUT b. SUE c. CAL d. BIGarrow_forward
- A very long, thin wire fixed along the x axis has a linear charge density of 3.2 C/m. a. Determine the electric field at point P a distance of 0.50 m from the wire. b. If there is a test charge q0 = 12.0 C at point P, what is the magnitude of the net force on this charge? In which direction will the test charge accelerate?arrow_forwardA simple pendulum has a small sphere at its end with mass m and charge q. The pendulums rod has length L and its weight is negligible. The pendulum is placed in a uniform electric field of strength E directed vertically upward. What is the period of oscillation of the sphere if the electric force is less than the gravitational force on the sphere? Assume the oscillations are small. FIGURE P24.63arrow_forwardA glass sphere with radius 4.00 mm, mass 85.0 g, and total charge 4.00 C is separated by 150.0 cm from a second glass sphere 2.00 mm in radius, with mass 300.0 g and total charge 5.00 C. The charge distribution on both spheres is uniform. If the spheres are released from rest, what is the speed of each sphere the instant before they collide?arrow_forward
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