Exam 23: Electric Fields

Three point charges are positioned on the x axis. If the charges and corresponding positions are +32 μC at x = 0, +20 μC at x = 40 cm, and −60 μC at x = 60 cm, what is the magnitude of the electrostatic force on the +32-μC charge?

Three pith balls supported by insulating threads hang from a support. We know that ball X is positively charged. When ball X is brought near balls Y and Z without touching them, it attracts Y and repels Z. Since pith is an insulating material, we can conclude that

Two uniform rods, each of length 2.0 m, are bent to form semicircles. One rod has a charger per unit lent of 1.5 nC/m, and the other has a charge per unit length of -1.5 nC/m. The semicircles are joined to make a circle. What is the magnitude of the electric field at the center of the circle?

If Q = 16 nC, a = 3.0 m, and b = 4.0 m, what is the magnitude of the electric field at point P?

A negatively charged particle is moving in the +x-direction when it enters a region with a uniform electric field pointing in the +x-direction. Which graph gives its position as a function of time correctly? (Its initial position is x = 0 at t = 0.)

Three 2.50 μC charges are placed on tiny conducting spheres at the ends of 1.00 m-long strings that are connected at 120° angles as shown below. The magnitude, in N, of the force on any one of the charges is

A 40-μC charge is positioned on the x axis at x = 4.0 cm. Where should a −60-μC charge be placed to produce a net electric field of zero at the origin?

A +15-nC point charge is placed on the x axis at x = 1.5 m, and a −20-nC charge is placed on the y axis at y = −2.0m. What is the magnitude of the electric field at the origin?

In the figure, if Q = 30 μC, q = 5.0 μC, and d = 30 cm, what is the magnitude of the electrostatic force on q?

A particle (charge = +40 μC) is located on the x axis at the point x = −20 cm, and a second particle (charge = −50 μC) is placed on the x axis at x = +30 cm. What is the magnitude of the total electrostatic force on a third particle (charge = −4.0 μC) placed at the origin (x = 0)?

Identical point charges Q are placed at each of the four corners of a 3.0 m × 4.0 m rectangle. If Q = 40 μC, what is the magnitude of the electrostatic force on any one of the charges?

If a = 3.0 mm, b = 4.0 mm, Q₁ = −60 nC, Q₂ = 80 nC, and q = 30 nC in the figure, what is the magnitude of the electric force on q?

If Q = 80 nC, a = 3.0 m, and b = 4.0 m in the figure, what is the magnitude of the electric field at point P?

If a = 3.0 mm, b = 4.0 mm, Q₁ = 60 nC, Q₂ = 80 nC, and q = 24 nC in the figure, what is the magnitude of the electric force on q?

A charge of +80 μC is placed on the x axis at x = 0. A second charge of −50 μC is placed on the x axis at x = 50 cm. What is the magnitude of the electrostatic force on a third charge of 4.0 μC placed on the x axis at x = 30 cm?

A point charge Q is placed on the x axis at x = 2.0 m. A second point charge, −Q, is placed at x = 3.0 m. If Q = 40 μC, what is the magnitude of the electrostatic force on a 30-μC charge placed at the origin?

If Q = 20 μC and L = 60 cm, what is the magnitude of the electrostatic force on any one of the charges shown?

Two tiny metal spheres are fixed to the ends of a non-conducting string of length . Equal charges, +q, are placed on the metal spheres. Randall says that the force on the string has magnitude . Tilden says that the tension in the string has magnitude . Which one, if either, is correct?

Three pith balls supported by insulating threads hang from a support. We know that ball X is positively charged. When ball X is brought near balls Y and Z without touching them, it attracts Y and repels Z. Since pith is an insulating material, we can conclude that

Two charged particles, Q₁ and Q₂, are a distance r apart with Q₂ = 5Q₁. Compare the forces they exert on one another when is the force Q₂ exerts on Q₁ and is the force Q₁ exerts on Q₂.