Additional Problems

| 49 | Two point charges, and , are separated by 1.20 m. What is the electric potential midway between them?

| 50 | The work done by an electric force in moving a charge from point A to point B is . The electric potential difference between the two points is . What is the charge?

| 51 | ssm The electric potential energy stored in the capacitor of a defibrillator is 73 J, and the capacitance is . What is the potential difference that exists across the capacitor plates?

| 52 | Refer to Multiple-Concept Example 3 to review the concepts that are needed here. A cordless electric shaver uses energy at a rate of 4.0 W from a rechargeable 1.5-V battery. Each of the charged particles that the battery delivers to the shaver carries a charge that has a magnitude of . A fully charged battery allows the shaver to be used for its maximum operation time, during which of the charged particles pass between the terminals of the battery as the shaver operates. What is the shaver’s maximum operation time?

| 53 | A capacitor has a capacitance of . In the charging process, electrons are removed from one plate and placed on the other plate. When the potential difference between the plates is 450 V, how many electrons have been transferred?

| 54 | The drawing shows four point charges. The value of q is , and the distance d is 0.96 m. Find the total potential at the location P. Assume that the potential of a point charge is zero at infinity.

Problem 54

| 55 | ssm Two points, A and B, are separated by 0.016 m. The potential at A is +95 V, and that at B is +28 V. Find the magnitude and direction of the constant electric field between the points.

* | 56 | The drawing shows a uniform electric field that points in the negative y direction; the magnitude of the field is 3600 N/C. Determine the electric potential difference (a) between points A and B, (b) between points B and C, and (c) between points C and A.

Problem 56

* | 57 | Two hollow metal spheres are concentric with each other. The inner sphere has a radius of 0.1500 m and a potential of 85.0 V. The radius of the outer sphere is 0.1520 m and its potential is 82.0 V. If the region between the spheres is filled with Teflon, find the electric energy contained in this space.

** | 58 | Two particles each have a mass of . One has a charge of , and the other has a charge of . They are initially held at rest at a distance of 0.80 m apart. Both are then released and accelerate toward each other. How fast is each particle moving when the separation between them is one-third its initial value?

** | 59 | ssm www The potential difference between the plates of a capacitor is 175 V. Midway between the plates, a proton and an electron are released. The electron is released from rest. The proton is projected perpendicularly toward the negative plate with an initial speed. The proton strikes the negative plate at the same instant that the electron strikes the positive plate. Ignore the attraction between the two particles, and find the initial speed of the proton.

** | 60 | A positive charge of +q1 is located 3.00 m to the left of a negative charge −q2. The charges have different magnitudes. On the line through the charges, the net electric field is zero at a spot 1.00 m to the right of the negative charge. On this line there are also two spots where the potential is zero. Locate these two spots relative to the negative charge.

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