Exam 23: Electric Forces

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 charge of 50-μC is placed on the y axis at y = 3.0 cm and a 77-μC charge is placed on the x axis at x = 4.0 cm. If both charges are held fixed, what is the magnitude of the initial acceleration of an electron released from rest at the origin?

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

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 ​ ​

Rubber rods charged by rubbing with cat fur repel each other. Glass rods charged by rubbing with silk repel each other. A rubber rod and a glass rod charged respectively as above attract each other. A possible explanation is that

A point charge Q is placed on the x axis at x = −2.0 m. A second point charge, −Q, is placed at x = 1.0 m. If Q = 60 μC, what is the magnitude of the electrostatic force on a 40-μC charge placed at the origin?

A point charge Q is placed on the x axis at the origin. An identical point charge is placed on the x axis at x = −1.0 m and another at x = +1.0 m. If Q = 40 μC, what is the magnitude of the electrostatic force on the charge at x = +1.0 m?

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?

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

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

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.

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?

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?

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)?

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

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 particle (m = 50 g, q = 5.0 μC) is released from rest when it is 50 cm from a second particle (Q = −20 μC). Determine the magnitude of the initial acceleration of the 50-g particle.

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 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?

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?