Exam 23: Electric Fields

A particle (mass = 5.0 g, charge = 40 mC) moves in a region of space where the electric field is uniform and is given by E_x = 2.5 N/C, E_y = E_z = 0. If the velocity of the particle at t = 0 is given by v_y = 50 m/s, v_x = v_z = 0, what is the speed of the particle at t = 2.0 s?

A point charge (−5.0 μC) is placed on the x axis at x = 4.0 cm, and a second charge (+5.0 μC) is placed on the x axis at x = −4.0 cm. What is the magnitude of the electric force on a third charge (+2.5 μC) placed on the y axis at y = 3.0 cm?

A particle (mass = 4.0 g, charge = 80 mC) moves in a region of space where the electric field is uniform and is given by E_x = −2.5 N/C, E_y = E_z = 0. If the velocity of the particle at t = 0 is given by v_x = 80 m/s, v_y = v_z = 0, what is the speed of the particle at t = 2.0 s?

An alpha particle (charge = +2e) is sent at high speed toward a gold nucleus (charge +79e). What is the electrical force acting on the alpha particle when it is at a distance of 2 × 10−¹⁴ m away from the gold nucleus? (e = 1.6 × 10−¹⁹ C)

If a = 60 cm, b = 80 cm, Q = −6.0 nC, and q = 6.0 nC, what is the magnitude of the electric field at point P in the figure?

A charge Q is placed on the x axis at x = +4.0 m. A second charge q is located at the origin. If Q = +75 nC and q = −8.0 nC, what is the magnitude of the electric field on the y axis at y = +3.0 m?

In a diagram of charges and electric field lines charge has twelve field lines going outward from it and charge has three field lines going into it. If one of the charges is 100 nC, what is the other one?

When a positive charge q is placed in the field created by two other charges Q₁ and Q₂, each a distance r away from q, the acceleration of q is

A +20-nC point charge is placed on the x axis at x = 2.0 m, and a −25-nC point charge is placed on the y axis at y = −3.0 m. What is the direction of the electric field at the origin?

The symbol appears in Coulomb's law because we use independently defined units for

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 the knot at the center is

A positively charged particle is moving in the +y-direction when it enters a region with a uniform electric field pointing in the +x-direction. Which of the diagrams below shows its path while it is in the region where the electric field exists. The region with the field is the region between the plates bounding each figure. The field lines always point to the right. The x-direction is to the right; the y-direction is up.

If a = 60 cm, b = 80 cm, Q = −4.0 nC, and q = 1.5 nC, what is the magnitude of the electric field at point P?

The electron gun in a television tube accelerates electrons (mass = 9.11 × 10−³¹ kg, charge = 1.60 × 10−¹⁹ C) from rest to 3.00 × 10⁷ m/s within a distance of 2.00 cm. What electric field is required?

If Q = 25 μC, q = 10 μC, and L = 40 cm in the figure, what is the magnitude of the electrostatic force on q?

A particle (m = 20 mg, q = −5.0 μC) moves in a uniform electric field of 60 N/C in the positive x direction. At t = 0, the particle is moving 30 m/s in the positive x direction and is passing through the origin. Determine the maximum distance beyond x = 0 the particle travels in the positive x direction.

A point charge Q is placed at the origin. A second charge, 2Q, is placed on the x axis at x = −3.0 m. If Q = 50 μC, what is the magnitude of the electrostatic force on a third point charge, −Q, placed on the y axis at y = +4.0 m?

Enrico says that positive charge is created when you rub a glass rod with silk, and that negative charge is simply the absence of positive charge. Rosetta says that negative charge is created and that positive charge is the absence of positive charge. (She has heard that Ben Franklin should have reversed the signs he associated with the charges.) Which one, if either, is correct?

If a = 3.0 mm, b = 4.0 mm, Q₁ = 60 nC, Q₂ = −80 nC, and q = 36 nC in the figure, what is the magnitude of the electric force on q?

Two identical pith balls supported by insulating threads hang side by side and close together, as shown below. One is positively charged; the other is neutral. We can conclude that