Physics Assigments

Two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of magnitude F due to the other. With time, charge gradually diminishes on both spheres by leaking off. When each of the spheres has lost half its initial charge, what will be the magnitude of the electrostatic force on each one?

1/4 F

The force of attraction that a -40.0 μC point charge exerts on a +108 μC point charge has magnitude 4.00 N. How far apart are these two charges? (k = 1/4πε0 = 8.99 × 10^9 N ∙ m^2/C^2)

3.12 m

A small glass bead has been charged to 1.9 nC. What is the strength of the electric field 2.0 cm from the center of the bead? (k = 1/4πε0 = 8.99 × 109 N ∙ m2/C2)

4.3 × 104 N/C

How many electrons are necessary to produce 1.0 C of negative charge? (e = 1.60 × 10^-19 C)

6.3 × 10^18

Three equal charges +Q are at three of the corners of a square on a side d. A fourth charge +Q of equal magnitude is at the center of the square as shown in the figure. Which one of the arrows shown represents the net force acting on the charge at the center of the square?

B

Three equal-magnitude point charges of varying signs are placed at three of the corners of a square of side d as shown in the figure. Which one of the arrows shown represents the direction of the net electric field at the vacant corner of the square?

B

Four point charges Q of equal magnitude and sign are arranged on three of the corners of the square of side d as shown in the figure Which one of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

D

In outer space, a positive charge q is released near a positive fixed charge Q, as shown in the figure. As q moves away from Q, what is true about the motion of q? (There may be more than one correct choice.)

It will move with decreasing acceleration. It will move with increasing speed.

The figure shows electric field lines arising from two small charged particles P and Q. Consider the following two statements:(i) The charge on P is smaller than the charge on Q.(ii) The electrostatic force on P is smaller than the force on Q.Which of the above statements are true?

Only (i) is true.

The figure shows two unequal charges, +q and -Q. Charge -Q has greater magnitude than charge +q. Point X is midway between the charges. In what section of the line will there be a point where the resultant electric field is zero?

VW

X and Y are two initially uncharged metal spheres on insulating stands, and they are in contact with each other. A positively charged rod R is brought close to X as shown in part (a) of the figure. Sphere Y is now moved away from X, as shown in part (b). What are the final charge states of X and Y?

X is negative and Y is positive

Electrically neutral objects cannot exert an electrical force on each other, but they can exert a gravitational force on each other.

false

Four tiny charged particles (two having a charge +Q and two having a charge -Q) are distributed on the x- and y-axes as shown in the figure. Each charge is equidistant from the origin. In which direction is the net electric field at the point P on the y-axis?

upwards and towards the left

Three identical 3.0-µC charges are placed at the vertices of an equilateral triangle that measures 30 cm on a side. What is the magnitude of the electrostatic force on any one of the charges? (k = 1/4πε0 = 9.0 × 109 N ∙ m2/C2)

1.6 N

As shown in the figure, three small charges are equally spaced on the arc of a circle that is centered at the charge Q, where Q = +23 nC and all the other quantities are accurate to two significant figures. What is the magnitude of the net electric force on the charge Q due to the other three charges? (k = 1/4πε0 = 9.0 × 109 N ∙ m2/C2)

2.6 × 10-4 N

A +5.00-μC point charge is placed at the 0.0 cm mark of a meter stick and a -4.00-μC point charge is placed at the 50.0 cm mark. At what point on a line through the ends of the meter stick is the electric field equal to zero?

4.7 m from the 0 cm mark

An electron is projected with an initial velocity v0 = 8.4 × 107 m/s along the y-axis, which is the centerline between a pair of charged plates, as shown in the figure. The plates are 1.0 m long and are separated by 0.10 m. A uniform electric field of magnitude E in the +x-direction is present between the plates. If the magnitude of the acceleration of the electron is measured to be what is the magnitude of the electric field between the plates? (e = 1.6 × 10-19 C, melectron = 9.11 × 10-31 kg) . NOTE: In this problem you use Newton's Second Law, F=ma to find the force, then use the Force-Electric Field equation to find the electric field.

51,000 N/C

The zirconium nucleus contains 40 protons, and an electron is 1.0 nm from the nucleus. What is the electric force on the electron due to the nucleus? ( e = 1.60 × 10-19 C, k = 1/4πε0 = 9.0 × 109 N ∙ m2/C2)

9.2 nN

Three equal-magnitude point charges of varying signs are placed at the corners of a square of side d as shown in the figure. Which one of the arrows shown represents the direction of the net electric field at the center of the square?

A

Two very small plastic balls of equal mass are released from rest. One of them carries +10 µC of excess charge and the other one carries +1µC of charge. No other charges or fields are present. Which of the following statements are true about them as they move away from each other? (There may be more than one correct choice.)

The balls always have accelerations of equal magnitude. The speed of the balls keeps increasing.

if two objects are electrically attracted to each other,

the objects could be electrically neutral