ch21

If three uncharged styrofoam balls are placed together and agitated so that one gains ++3 CC of charge and another gains ++4 CC of charge, how much charge must there be on the third one

-7C

Four ++2 μCμC charges are placed at the positions (10 cmcm, 0 cmcm), (−−10 cmcm, 0 cmcm), (0 cmcm, 10 cmcm), and (0 cmcm, −−10 cmcm) such that they form a diamond shape centered on the origin. A charge of ++5 μCμC is placed at the origin. If the force between a ++2 μCμC and a ++5 μCμC charge separated by 10 cmcm has a magnitude of 9 NN, which of the following can we say about the force on the ++5 μCμC charge at the origin in this case?

0

A very long straight wire has charge per unit length 1.45×10^−10 C/m. At what distance from the wire is the magnitude of the electric field equal to 2.59 N/C ? Use 8.85×10−12 C2/(N⋅m2) for the permittivity of free space, and use π=3.14159.

1.01 m bc E=2k (wavelength)/r

Two protons and an electron are fixed on the corners of a rectangle, as shown. One proton is at (0 nm, 1.75 nm) and the other proton is at (1.15 nm, 0 nm). The electron is fixed at (1.15 nm, 1.75 nm). What is the magnitude of the force on the electron due to the two protons?

1.90 × 10^-10 N

Two protons and an electron are fixed on the corners of a rectangle, as shown. One proton is at (0 nm, 1.75 nm) and the other proton is at (1.15 nm, 0 nm). The electron is fixed at (1.15 nm, 1.75 nm). What is the angle made by the force on the electron due to the two protons, measured with respect to the +x axis?

203 dgs

A proton is placed in a uniform electric field of 2500 N/C. 1. Calculate the magnitude of the electric force felt by the proton.

4.0×10^−16N bc F=qE

Calculate the proton's speed after 2.00 μs in the field, assuming it starts from rest.

4.8×10^5 m/s

A proton and an electron are fixed 1.75 nm apart from each other. What is the force exerted on the electron due to the proton?

7.53 × 10-11 N, towards the proton

Two small spheres spaced 20.0 cm apart have equal charge. How many excess electrons must be present on each sphere if the magnitude of the force of repulsion between them is 3.33×10^−21 N?

761 bc N=q/e

Which of the following statements are true?

A positive charge and a negative charge attract each other.Electric charge is conserved.Two negative charges repel each other.Electric charge is quantized.

Calculate the proton's acceleration.

A=F/m= 2.39 x 10^11 m/s^2

The strength of the electric field at a certain distance from a point charge is represented by E. What is the strength of the electric field at twice the distance from the point charge?

At twice the distance, the strength of the field is E/4.

Which of the following statements are true?

Electric field lines near positive point charges radiate outward.In a uniform electric field, the field lines are straight, parallel, and uniformly spaced.The electric force acting on a point charge is proportional to the magnitude of the point charge.

Which of the following statements are true for electric field lines?

Electric field lines point away from positive charges and toward negative charges.At every point in space, the electric field vector at that point is tangent to the electric field line through that point.Electric field lines can never intersect.

The charge imbalance that results from this movement of charge will generate an additional electric field in the region within the rod. In what direction will this field point?

It will point to the left and oppose the initial applied field.

Using the setup from the first question, imagine that you briefly touch the negatively charged rod to the can (assume that this rod is conducting for the sake of effect). You then hold the two rods at equal distances on either side of the can. What does the can do?

Rolls toward the positively charged rod

Two charged objects are separated by some distance. The charge on the first object is greater than the charge on the second object. How does the force between the two objects compare?

The charged objects exert electrostatic forces on each other that are equal in magnitude and opposite in direction.

What is the motion of the negative electrons and positive atomic nuclei caused by the external field?

The electrons move to the left and the nuclei are almost stationary.

A positively charged rod is brought close to one end of an uncharged metal rod but does not actually touch it. What type of charge does the end of the metal rod closest to the positively charged rod acquire?

The end of the metal rod closest to the positively charged rod acquires a negative charge.

A plastic rod is rubbed with a fur. During the rubbing process, the rod acquires a negative charge. What type of charge does the fur acquire?

The fur acquires a positive charge.

A charge of ++0.001 CC is 1 mm to your right and another charge of ++1000 CC is 1 mm to your left. You are holding a charge of −−1 CC. Which of the following statements is/are true?

The magnitude of the force on the charge you are holding would be the same if it were ++1 CC instead of −−1 CC.The force on the charge you are holding from the charge on your left is 1,000,000 times as large as the force from the charge on your right.

When a point charge of +q is placed on one corner of a square, an electric field strength of 2 N/C is observed at the center of the square. Suppose three identical charges of +q are placed on the remaining three corners of the square. What is the magnitude of the net electric field at the center of the square?

The magnitude of the net electric field at the center of the square is 0 N/C

What is the force felt by the electrons and the nuclei in the rod when the external field described in the problem introduction is applied? (Ignore internal fields in the rod for the moment.)

The nuclei experience a force to the right and the electrons experience a force to the left.

Is it possible for the electric field between two positive charges to equal zero along the line joining the two charges?

Yes, regardless of the magnitude of the two charges.

An electric dipole is situated as shown in (Figure 2). What direction is the electric field at location P?

do these ch 21 prelect questions! #5bc

Two charged objects separated by some distance attract each other. If the charges on both objects are doubled with no change in distance between them, what happens to the magnitude of the force between the objects?

it quadruples

Consider the situation in the figure below, where two charged rods are placed a distance d on either side of an aluminum can. What does the can do? (fig has a can in middle n neg charged rod on left and pos charged rod on right)

it stay still

Now, consider the situation shown in the figure below. What does the can do? (fig has a can in middle and pos rods on left n right)

it stay still

Imagine that the rightward current flows in the rod for a short time. As a result, what will the net charge on the right and left ends of the rod become?

left end negative and right end positive

A negative point-charge of charge −Q is situated as shown in (Figure 1). Suppose another negative charge q0 is placed at location P. The electric field at location P due to the charge −Q is __________, and the electric force exerted on the charge q0 at location P is ___________.

to the left, to the right

You are holding a positive charge and there are positive charges of equal magnitude 1 mm to your north and 1 mm to your east. What is the direction of the force on the charge you are holding?

to the southwest