Find the total Coulomb force on a charge of 2.00 nC located at x = 4.00 cm in Figure 18.52(b), given that q = 1.00 μC . (а) x (cm) -29 10 +q +g (b) + + + x (cm) -9 10 -29 +9 +3q Figure 18.52(b) Point charges located at 1.00, 5.00, 8.00, and 14.0 cm along the x-axis. Choose the two correct forces below. 0.252 N to the left 0.252 N to the right -0.252 N to the left

Review. Two insulating spheres have radii r1 and r2, masses m1 and m2, and uniformly distributed charges q1 and q2. They are released from rest when their centers are separated by a distance d. (a) How fast is each moving when they collide? (b) What If? It the spheres were conductors, would their speeds be greater or less than those calculated in part (a)? Explain.

Using Figure 18.43, explain, in terms of Coulomb's law, why a polar molecule (such as in Figure 18.43) is attracted by both positive and negative charges Figure 18.43 Schematic representation of the outer electron cloud of a neutral water molecule. The electrons spend more time near the oxygen than the hydrogens, giving a permanent charge separation as shown. Water is thus a polar molecule. It is more easily affected by electrostatic forces than

(a) What is the electric field 5.00 m from die center of the terminal of a Van de Graaff with a 3.00-mC charge, noting that the field is equivalent to that of a point charge at the center of the terminal? (b) At this distance, what force does the field exert on a 2.00C charge on the Van de Graaff’s belt?

Two charges Q1(1+2.00C) and Q2(+2.00C are placed symmetrically along the x-axis at x=3.00cm . Consider a charge Q3 of charge +4.00C and mass 10.0 mg moving along the y-axis. If Q3 starts from rest at y= 2.00 cm, what is its speed when it reaches y = 4.00 cm?

An amoeba has 1.001016protons and a net charge of 0.300 pC. (a) How many fewer electrons are there than protons? (b) If you paired them up, what fraction of the protons would have no electrons?

(a) By what factor must you change the distance between two point charges to change the force between them by a factor of 10? (b) Explain how the distance can either increase or decrease by this factor and still cause a factor of 10 change in the force

(a) Would life be different if the electron were positively charged and the proton were negatively charged? (b) Does the choice of signs have any bearing on physical and chemical interactions? Explain your answers.

A simple and common technique for accelerating electrons is shown in Figure 18.55, where there is a uniform electric field between two plates. Electrons are released, usually from a hot filament, near the negative plate, and there is a small hole in the positive plate that allows the electrons to continue moving. (a) Calculate the acceleration of the electorn if the field strength is 2.50104 N/C. (b) Explain why the electron will not be pulled back to the positive plate once it moves through the hole.

(a) Using the symmetry of the arrangement, show that the electric field at the center of the square in figure 18.46 is zero if the charges on the four comers are exactly equal. (b) Show that this is also true for any combination of charges in which qa= qd and qa = qc