Question 1

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

Accepted Answer

The total electric charge in an isolated system remains constant during any process.

Question 2

A neutral metal sphere is touched by a positively charged rod. What is the resulting charge on the sphere, and by what process did this occur?

Accepted Answer

The sphere becomes positively charged by conduction.

Question 3

Which of the following materials is most likely to be a good electrical conductor?

Accepted Answer

Copper

Question 4

A charged rod is brought near, but does not touch, a neutral metal sphere. The sphere is then grounded while the rod is still nearby. What is the final charge on the sphere after the ground connection and the rod are both removed?

Accepted Answer

The sphere is positively charged.

Question 5

Which equation correctly expresses Coulomb’s Law for the magnitude of 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

A proton and an electron are separated by a distance $$r. $$What is the direction of the electric force on the electron due to the proton?

Accepted Answer

Toward the proton

Question 7

The electric field at a distance $$r$$ from a point charge $$Q is $$given by which of the following expressions?

Accepted Answer

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

Question 8

A small particle with charge $$q$$ and mass $$m is $$released from rest in a uniform electric field $$E. $$What is its acceleration?

Accepted Answer

$$a = \frac{qE}{m}$$

Question 9

Which of the following best describes the electric field inside a conductor in electrostatic equilibrium?

Accepted Answer

It is zero.

Question 10

A thin ring of radius $$a$$ carries a total charge $$+Q$$ distributed uniformly. What is the electric field at a point on the axis of the ring, a distance $$x$$ from the center?

Accepted Answer

$$E = \frac{1}{4\pi\$$varepsilon_0$$} \frac{Qx}{(x^2$ + a^2$)^{3/2}$$}$

Question 11

Which of the following is true about electric field lines?

Accepted Answer

They never cross each other.

Question 12

A parallel-plate capacitor is constructed with two large plates separated by a small distance $$d. If $$the plates carry equal and opposite charges with surface charge density $$\sigma$$, what is the electric field between the plates (neglecting edge effects)?

Accepted Answer

$$E = \frac{\sigma}{\$$varepsilon_0$$}$$

Question 13

Gauss’s law states that the net electric flux through a closed surface is proportional to which of the following?

Accepted Answer

The total charge enclosed by the surface

Question 14

A solid nonconducting sphere of radius $$R$$ has a uniform charge density and total charge $$Q. $$What is the electric field at a distance $$r \u003c R$$ from the center?

Accepted Answer

$$E = \frac{1}{4\pi\$$varepsilon_0$$} \frac{Qr}{R^3$}$$

Question 15

The electric potential $$V at a $$distance $$r$$ from a point charge $$Q ($$with $$V = 0 at $$infinity) is given by:

Accepted Answer

$$V = \frac{1}{4\pi\$$varepsilon_0$$} \frac{Q}{r}$$

Question 16

A proton is released from rest in a uniform electric field of $$E = 1000\ \mathrm{N/C}. $$What is the change in its electric potential energy after moving $$0.01\ \mathrm{m} in $$the direction of the field?

Accepted Answer

$$\Delta U = -qEd$$

Question 17

Which of the following statements about equipotential surfaces is correct?

Accepted Answer

Equipotential surfaces are always perpendicular to electric field lines.

Question 18

The energy gained by an electron moving through a potential difference of $$1\ \mathrm{V} is $$called:

Accepted Answer

1 electron volt (eV)

Question 19

A water molecule has a dipole moment $$p$$ and is placed in a uniform electric field $$E. $$What is the maximum torque experienced by the molecule?

Accepted Answer

$$	au_{max} = pE$$

Electric Charge, Electric Field, and Electric Potential: Study Notes for Physics Majors

Study Guide - Practice Questions

Study Guide - Flashcards