Q: A charge of $$q = 2 \times 10$$^{-9}$$ \ C is $$placed in an electric field of $$E = 4 \times 10^5$ \ N/C. $$What is the force experienced by the charge?

$$F = 8 \times 10$$^{-4}$$ \ N$$

Q: Which equation represents Gauss's Law for electric flux through a closed surface?

$$\Phi_E = \frac{Q_{\text{enclosed}}}{\$$varepsilon_0$$}$$

Question 1

A plastic rod is rubbed with wool, and the rod becomes negatively charged. Which statement best explains this observation?

Accepted Answer

Electrons are transferred from the wool to the plastic rod.

Question 2

Which of the following best describes the law of conservation of charge?

Accepted Answer

The total charge in an isolated system remains constant, even though charges may be transferred between objects.

Question 3

Two point charges, $$q_1 = 5$$ \ \mu C$$ and q_2$ = -3 \ \mu C$$, are placed 0.2 m apart. What is the magnitude of the force between them? (Use $$k_e = 8.99 	imes 10^9$ \ N \cdot m^2$/C^2$)

Accepted Answer

$$F = 3.37 	imes 10^2$ \ N$$

Question 4

Which of the following statements about conductors and insulators is correct?

Accepted Answer

Charges move freely in conductors but are stuck in place in insulators.

Question 5

A charge of $$q = 2 	imes 10$$^{-9}$$ \ C is $$placed in an electric field of $$E = 4 	imes 10^5$ \ N/C. $$What is the force experienced by the charge?

Accepted Answer

$$F = 8 	imes 10$$^{-4}$$ \ N$$

Question 6

Which equation correctly represents Coulomb's Law for the force between two point charges?

Accepted Answer

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

Question 7

A glass rod is rubbed with silk and becomes positively charged. What happens at the atomic level?

Accepted Answer

Electrons are transferred from the glass rod to the silk.

Question 8

A point charge $$Q$$ creates an electric field at a distance $$r. $$Which equation gives the electric field at that point?

Accepted Answer

$$E = k_e \frac{Q}{r^2$}$$

Question 9

If three point charges are placed at the vertices of a triangle, how do you determine the net force on one of the charges?

Accepted Answer

Calculate the vector sum of the forces from the other two charges using Coulomb's Law.

Question 10

Which of the following best describes the direction of the electric field created by a positive point charge?

Accepted Answer

The field points away from the charge.

Question 11

A dipole consists of charges $$+q$$ and $$-q$$ separated by distance $$d. $$What is the dipole moment?

Accepted Answer

$$p = qd$$

Question 12

Which statement about electric field lines is correct?

Accepted Answer

The density of field lines indicates the strength of the electric field.

Question 13

A uniformly charged rod of length $$L$$ and total charge $$Q$$ has a linear charge density $$\lambda. $$Which equation defines $$\lambda$$?

Accepted Answer

$$\lambda = \frac{Q}{L}$$

Question 14

A disk of radius $$R$$ has a uniform surface charge density $$\sigma. $$What is the total charge $$Q on $$the disk?

Accepted Answer

$$Q = \sigma \pi R^2$

Question 15

Which equation represents Gauss's Law for electric flux through a closed surface?

Accepted Answer

$$\Phi_E = \frac{Q_{	ext{enclosed}}}{\$$varepsilon_0$$}$$

Question 16

A charge $$q$$ moves a distance $$s in a $$uniform electric field $$E$$ from the negative plate to the positive plate. What is the change in electric potential energy?

Accepted Answer

$$\Delta U = qEs$$

Question 17

Which of the following is the correct SI unit for electric flux?

Accepted Answer

$$N \cdot m^2$ / C$$

Question 18

A point charge $$q is $$placed at the center of a cube. According to Gauss's Law, what is the total electric flux through the cube?

Accepted Answer

$$\Phi_E = \frac{q}{\$$varepsilon_0$$}$$

Question 19

A charge $$q is $$moved from point $$A to $$point $$B in an $$electric field. Which equation gives the work done by the electric field?

Accepted Answer

$$W = q \Delta V$$

Electric Charge, Coulomb's Law, Electric Fields, Gauss's Law, and Electric Potential

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