Exam 1: The Electric Field I: Discrete Charge Distributions

An electric dipole p makes an angle of 30 $\degree$ with a uniform electric field of magnitude 300 N/C. If the torque on the dipole is 3.00 * 10^-12 N · m then calculate the magnitude of the dipole moment p.

Which of the following statements is not true?

An electron is released from rest in a uniform electric field. If the electric field is 1.25 kN/C, at the end of 20 ns the electron's velocity will be approximately

Two positive charges (+8.0 mC and +2.0 mC) are separated by 300 m. A third charge is placed at distance r from the +8.0 mC charge in such a way that the resultant electric force on the third charge due to the other two charges is zero. The distance r is

If all the charges are 15 cm from the origin (the crossing point of the vertical and horizontal lines) in the above figure and Q = +3.0 $\mu$ C, then calculate the magnitude of the net force on a charge of +Q placed at the origin.

Two charges Q₁ and Q₂ are 8.0 cm apart. Charge Q₁ = 5.0 nC and Q₂ = -5.0 nC. The magnitude of the electric field at point P, 3.0 cm from the midpoint of the line joining Q₁ and Q₂, is

Which of the following statements about electric field lines is not true?

A molecule of HCl has a dipole moment of 3.39 * 10^-30 C · m. If we assume full donation of the hydrogen electron to the chlorine, then calculate the distance between the charge centers.

An electron (q = +e) and a positron (q = +e) can combine to give off two gamma rays. The net change in the algebraic sum of the charges is

Two charges Q₁ and Q₂ are a distance d apart. If the electric field is zero at a distance of 3d/4 from Q₁ (towards Q₂), then what is the relation between Q₁ and Q₂?

How many electrons must be transferred to a body to produce a charge of 125 nC?

Two small spheres repel one another electrostatically. Which of the following statements must be true?

A proton is about 2000 times more massive that an electron but they both have charges of the same magnitude. The magnitude of the force on an electron by a proton is ____ the magnitude of the force on the proton by the electron.

Use the picture for the next problem. A conducting sphere has a net charge of -q and of mass m is suspended from the ceiling by a light string. A uniform electric field E is applied vertical down on the sphere. -If m = 1 g, q = 1 $\mu$ C and E = 5000 N/C, the tension T in the string is

If a charge of +2Q were placed at the origin (the crossing point of the vertical and horizontal lines) of the above figure, into which quadrant would it feel a net force?

Three charges are located at 100-m intervals along a horizontal line: a charge of -3.0 C on the left, +2.0 C in the middle, and +1.0 C on the right. What is the resultant force on the 1.0 C charge due to the other two?

In the diagram, Q₁ = 6.0 $\mu$ C and Q₂ = -6.0 $\mu$ C. The electric field at point (2, 0) is

Two small spheres, each with mass m = 3.0 g and charge q, are suspended from a point by threads of length L = 0.22 m. What is the charge on each sphere if the threads make an angle $\theta$ = 15º with the vertical?

Three charges Q₁, Q₂, and Q₃, each equal to 6.4 *10^-19 C, are in a straight line. The distance between neighboring charges is 60 nm. The magnitude of the electric field at P, which is 80 nm from Q₂ on a line at right angles to the line between Q₁ and Q₃, is

If nonelectric forces are negligible, a positively charged particle released from rest in a nonuniform electric field