The figure below shoes the cross section of three infinite sheets intersecting at equal angles. The sheets all have surface charge density σ. * Find the electric field everywhere. O a. E O b. E = = 20 350 За Επ ○ C. E E0 За Od. E= O e. E = Of E=0 200 250

(a) What magnitude point charge creates a 10,000 N/C electric field at a distance of 0.250 m? (b) How large is the field at 10.0 m?

(a) What is the direction of the total Coulomb force on q in Figure 18.46 if q is negative, qa= qcand both are negative, and qb= qcand both are positive? (b) What is the direction of the electric field at the center of the square in this situation?

Unreasonable Results 64. (a) Calculate the electric field strength near a 10.0 cm diameter conducting sphere that has 1.00 C of excess charge on it. (b) What is unreasonable about this result? (c) Which assumptions are responsible?

(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 nonconducting wall carries charge with a uniform density of 8.60 C/cm2. (a) What is the electric field 7.00 cm in front of the wall if 7.00 cm is small compared with the dimensions of the wall? (b) Does your result change as the distance from the wall varies? Explain.

(a) Find the magnitude of the electric force between a Na+ ion and a Cl ion separated by 0.50 nm. (b) Would the answer change if the sodium ion were replaced by Li+ and the chloride ion by Br ? Explain.

Unreasonable results A wrecking yard inventor wants to pick up cars by charging a 0.400 m diameter ball and inducing an equal and opposite charge on the car. If a car has a 1000 kg mass and the ball is to be able to lift it from a distance of 1.00 m: (a) What minimum charge must be used? (b) What is the electric field near the surface of the ball? (c) Why are these results unreasonable? (d) Which premise or assumption is responsible?

A thin, square, conducting plate 50.0 cm on a side lies in the xy plane. A total charge of 4.00 108 C is placed on the plate. Find (a) the charge density on each face of the plate, (b) the electric field just above the plate, and (c) the electric field just below the plate. You may assume the charge density is uniform.

Earth has a net charge that produces an electric field of approximately 150 N/C downward at its surface. (a) What is the magnitude and sign of the excess charge, noting the electric field of a conducting sphere is equivalent to a point charge at its center? (b) What acceleration will the field produce on a free electron near Earth’s surface? (c) What mass object with a single extra electron will have its weight supported by this field?