Q: What is the value of the electrostatic constant $$K in SI $$units?

$$8.99 \times 10^9$\ \mathrm{N\,m^2$/C^2$$}$

Question 1

Which of the following statements best describes the process of charging an object by friction?

Accepted Answer

Frictional forces add or remove charge from an object, resulting in the object becoming charged.

Question 2

According to the charge model, what happens when two objects with like charges are brought near each other?

Accepted Answer

They repel each other.

Question 3

Which of the following is the SI unit of electric charge?

Accepted Answer

Coulomb

Question 4

A glass rod rubbed with silk becomes positively charged. What is the sign of the charge on the silk?

Accepted Answer

Negative

Question 5

Which equation correctly expresses Coulomb’s Law for the force between two point charges $$q_1$$ and $$q_2$$ separated by a distance $$r$$?

Accepted Answer

$$F = K \frac{|q_1$||q_2$|}{r^2$}$$

Question 6

What is the value of the electrostatic constant $$K in SI $$units?

Accepted Answer

$$8.99 	imes 10^9$\ \mathrm{N\,m^2$/C^2$$}$

Question 7

If the distance between two charges is halved, by what factor does the electrostatic force between them change?

Accepted Answer

It increases by a factor of 4.

Question 8

Which of the following best describes a conductor?

Accepted Answer

A material in which charge moves easily.

Question 9

What is the charge of a proton and an electron, respectively?

Accepted Answer

+e and -e

Question 10

A neutral atom becomes a positive ion when:

Accepted Answer

It loses an electron.

Question 11

Which of the following equations gives the electric field $$\vec{E} at a $$distance $$r$$ from a point charge $$q$$?

Accepted Answer

$$\vec{E} = \frac{1}{4\pi\$$epsilon_0$$} \frac{q}{r^2$} \hat{r}$$

Question 12

A plastic rod is rubbed with wool and becomes negatively charged. What happens at the atomic level?

Accepted Answer

Electrons are transferred from the wool to the plastic rod.

Question 13

Which of the following best describes the electric field?

Accepted Answer

A vector field that assigns a force per unit charge to every point in space.

Question 14

If a probe charge $$q$$ experiences a force $$\vec{F} at a $$point in space, what is the electric field $$\vec{E} at $$that point?

Accepted Answer

$$\vec{E} = \frac{\vec{F}}{q}$$

Question 15

Which of the following is true about the force between two charges according to Newton’s third law?

Accepted Answer

The forces are equal in magnitude and opposite in direction.

Question 16

A glass bead with a charge of $$+10\ \mathrm{nC} is $$placed 1.0 cm below a plastic sphere with a charge of $$-10\ \mathrm{nC}. $$What is the direction of the electrostatic force on the glass bead?

Accepted Answer

Upward, toward the plastic sphere.

Question 17

Which of the following best describes an insulator?

Accepted Answer

A material in which electrons are tightly bound and charge does not move freely.

Question 18

What is the value of the permittivity constant $$\$$epsilon_0$$ in SI units?

Accepted Answer

$$8.85 	imes 10$$^{-12}$$\ \mathrm{C^2$/N\,m^2$}$$

Question 19

Which of the following is true about the units of a unit vector?

Accepted Answer

A unit vector has no units.

Electric Charge and Electric Fields: Fundamental Concepts and Applications

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