1.
Two positive point charges are separated by a distance R. If the distance between the charges is reduced to R/2, what happens to the total electric potential energy of the system?
Correct Answer
A. The total electric potential energy is doubled.
Explanation
When the distance between the charges is reduced to half, the electric potential energy of the system increases. This is because the potential energy is inversely proportional to the distance between the charges. As the distance decreases, the potential energy increases. In this case, since the distance is reduced to half, the potential energy doubles.
2.
Which one of the following statements best explains why it is possible to define an electrostatic potential in a region of space that contains an electrostatic field?
Correct Answer
D. The work required to bring two charges together is independent of the path taken.
Explanation
The correct answer explains that it is possible to define an electrostatic potential in a region of space that contains an electrostatic field because the work required to bring two charges together is independent of the path taken. This means that the amount of work needed to move the charges from one point to another is the same regardless of the specific route taken. This allows for the calculation of a consistent electrostatic potential in the region.
3.
Complete the following statement: The electron volt is a unit of
Correct Answer
A. energy.
Explanation
The electron volt is a unit of energy because it measures the amount of energy that an electron gains or loses when it moves through an electric potential difference of one volt. It is commonly used in physics and related fields to describe the energy levels and interactions of subatomic particles. Other options such as electric field strength, electric force, electric potential difference, and electric power are not correct because they represent different concepts and units of measurement in electromagnetism.
4.
Which one of the following statements is true concerning the work done by an external force in moving an electron at constant speed between two points in an electrostatic field?
Correct Answer
E. The work done depends only on the displacement of the electron.
Explanation
The work done by an external force in moving an electron at constant speed between two points in an electrostatic field depends only on the displacement of the electron. This means that the amount of work done is independent of the path taken by the electron or the total distance covered. The work done is determined solely by the initial and final positions of the electron, regardless of the speed at which it is moving.
5.
Two charged particles A and B are located near one another. Both the magnitude and direction of the force that particle A exerts on particle B is independent of
Correct Answer
E. The magnitude and direction of the force are dependent on all of the choices.
Explanation
The magnitude and direction of the force between charged particles A and B depend on all of the choices given. This means that the force is independent of the sign of charge B, the sign of charge A, the distance between A and B, and the magnitude of the charge on B. In other words, the force between the particles is determined by multiple factors and is not affected by any one specific factor.
6.
Two uncharged, conducting spheres, A and B, are held at rest on insulating stands and are in contact. A positively charged rod is brought near sphere A as suggested in the figure. While the rod is in place, someone moves sphere B away from A. How will the spheres be charged, if at all?
Correct Answer
C. SpHere A: Negative
SpHere B: Positive
Explanation
When the positively charged rod is brought near sphere A, it induces a separation of charges in sphere A. The negative charges in sphere A are attracted to the rod, leaving the positive charges behind. This results in sphere A becoming negatively charged. When sphere B is moved away from sphere A, there is no influence of the rod on sphere B. Therefore, sphere B remains uncharged. Hence, the spheres will be charged as follows: Sphere A will be negatively charged, and sphere B will be uncharged.
7.
Complete the following statement: When a glass rod is rubbed with silk cloth, the rod becomes positively charged as
Correct Answer
B. Negative charges are transferred from the rod to the silk.
Explanation
When a glass rod is rubbed with silk cloth, the rod becomes positively charged as negative charges are transferred from the rod to the silk.
8.
Three objects have a net charge. Objects A and B attract one another. Objects B and C also attract one another, but objects A and C repel one another. Which one of the following table entries is a possible combination of the signs of the net charges on these three objects?
Correct Answer
D. A: -
B: +
C: -
Explanation
Objects A and C repel one another, which means they have opposite charges. Objects B and C attract one another, which means they have opposite charges. Objects A and B attract one another, which means they have opposite charges. Therefore, a possible combination of the signs of the net charges on these three objects is A: - , B: + , C: -.