Problem 4: who is right? Two parallel, infinite planes of charge have charge densities +20 and -o as shown in Fig. O They are at a distance Lo from each other. Three students are asked to determine the electric field at points A and B, at a distance L above the top plane, and at a distance L below the bottom plane, respectively, as shown in the figure. Each student comes up with a different answer and a different explanation. Read carefully their statements below. The students are reminded that the electric field magnitude of an infinite plane of charge with charge density o is E = +26 +26 Figure 1: Two equivalent views of the two infinite parallel planes • Student 1 draws the sketch in Fig. 2 (top) and says: "I think from the outside we can think of the two planes as a single infinite plane with charge density +20 - oa =a, so then we know the electric field must be a/(2o) pointing upwards at point A and also a/(2co) pointing dounwards at B". • Student 2 draws the sketch in Fig. 2 (middle and says "I don't agree with you, I think you need to consider the effect of each single plane, so at point A there will be a field upwards due to the top plane with magnitude 20/(2ro) = a/ea, and at point B there will be a field upuards due to the bottom plane with magnitude a/(2o)". • Student 3 draws the sketch in Fig. 2 bottom and says "Do we just add the electric fields together? I'm going magnitude a/ea +a/(2eo) = 30/(2ro), and at point BI get the same 30/(2eo) but now pointing dounward" add up the field from each plane at both points. So at A I get a field upward of Evaluate each student's statement. Decide whether or not the statement is correct. If the student explanation contains incorrect reasoning, explain how the argument is flawed. studets 1%. 국 +936-6) student 2 studeut 3 % up +1 = 32 down Figure 2: Students' sletches.

A uniformly charge rod of length L and total charge Q lies along the x axis as show in the figure below. (Use the following a necessary: Q,L,d, and ke) a) Find the components of the electric field at the point P on the y axis a distance d from the origin b) What are the approximate values of the field components when d>>L? Explain why you would get these results

A -1.11 nC point charge is located inside a cavity of a hollow sphere of conducting material with charge 6.72 nC and of radius 10.0 cm.  Calculate the electric field 0.473 m from the point charge in units of N/C.  Assume answers are in the radial direciton such that if the field points radially away your answer will be positive and if the field points radially in your answer will be negative.  Give your numerical result to 3 significant figures and type in the units after your numerical answer.

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d B • 2d +20 व 2d d D - The figure above shows three very thin parallel planes of charge with equal separation 6 cm between them. The charge density of the middle plane is +4 nC/m² (nC = "nano Coulomb") and that of the two outer planes is -2nC/m². Your answers for the electric field must include the correct sign. We choose positive electric field along the positive y-direction. What is the electric field at point A? N/C Submit Answer Tries 0/2 What is the electric field at point B? N/C Submit Answer Tries 0/2 What is the electric field at point C? N/C Submit Answer Tries 0/2 What is the electric field at point D? N/C 1

Can you explain how the answer is 4.5?

Raya has two hoops that are charged and concentric, they have a radii of R and 2R respectively. They are found laying in the x and y plane. The smallest hoop has a uniform charge distribution with a density that is linear of -5.00 uC/m. At the point P which is 3R away from the center point of the hoops, the electric field is = to 0. Figure out the liner charge density on the biggest hoop. ÉR P 3R

Two 10-cm-diameter charged rings face each other, 25.0 cm apart. Both rings are charged to +40.0 nC. What is the electric field strength: Part A For general problem-solving tips and strategies for this topic, you may want to view a Video Tutor Solution of Charge on a Van De Graaff. at the midpoint between the two rings? Express your answer with the appropriate units. HÀ ? Value Units Submit Request Answer Part B at the center of the left ring? Express your answer with the appropriate units.

A sphere of radius a is filled with a positive charge with uniform density p. Then a smaller sphere of radius a/2 is carved out leaving and empty cavity as shown in the drawing. What is the direction and magnitude of the electric field at point A? (Hint: Use superposition concepts) Select one: ρα Oa. E: = upward 360 Ob. It is not possible to calculate because there is no spherical symmetry. 2pa downward C. E: = 360 ρα O d. E= upward 660 ρα ○ e. E = downward 860 ○ f. 7pa E= upward 860

O Macmillan Learning A thin metallic spherical shell of radius 46.1 cm has a total charge of 8.65 µC uniformly distributed on it. At the center of the shell is placed a point charge of 4.13 µC. What is the magnitude of the electric field at a distance of 22.9 cm from the center of the spherical shell? E = N/C What is the direction of the electric field? outward inward directionless