Q: What is the fundamental charge of an electron?

$-1.6 \times 10^{-19}\ \mathrm{C}$

Question 1

Which of the following best describes the difference between conductors and insulators?

Accepted Answer

Conductors allow charge to move easily through or along them, while insulators keep charge fixed in place.

Question 2

A neutral object is brought near a positively charged rod. What happens to the neutral object?

Accepted Answer

It becomes polarized, and the polarization force attracts the neutral object to the rod.

Question 3

What is the fundamental charge of an electron?

Accepted Answer

$-1.6 	imes 10^{-19}\ \mathrm{C}$

Question 4

If an object has $N_p$ protons and $N_e$ electrons, what is its net charge $q$?

Accepted Answer

$q = (N_p - N_e)e$

Question 5

Two identical metal spheres are initially neutral and are touching. A positively charged rod is brought near, then removed, and the spheres are separated. What are the final charges on the spheres?

Accepted Answer

Both spheres remain neutral: $Q_1 = 0$ and $Q_2 = 0$

Question 6

Which statement about electric forces is correct?

Accepted Answer

Like charges repel, opposite charges attract.

Question 7

A charged object is brought near a neutral metal sphere. What is the primary mechanism by which the sphere is attracted to the charged object?

Accepted Answer

Polarization of the sphere's electrons creates an induced dipole, resulting in an attractive force.

Question 8

Which equation correctly expresses the relationship between electric force and distance between two point charges?

Accepted Answer

$F \propto \dfrac{1}{r^2}$

Question 9

A negatively charged rod is brought near two identical, touching metal spheres. The rod is then removed, and the spheres are separated. What are the final charges on the spheres?

Accepted Answer

Both spheres remain neutral: $Q_1 = 0$ and $Q_2 = 0$

Question 10

Which of the following is true about charging by induction?

Accepted Answer

It involves polarizing an object and then separating it from the influence of the external charge before contact is broken.

Question 11

A metal sphere has a net charge of $+3.2 	imes 10^{-19}\ \mathrm{C}$. How many excess protons does it have?

Accepted Answer

$2$

Question 12

If the distance between two point charges is doubled, what happens to the electric force between them?

Accepted Answer

The force decreases by a factor of 4.

Question 13

Which of the following best explains why a charged balloon can stick to a neutral wall?

Accepted Answer

The charged balloon polarizes the molecules in the wall, creating an attractive force.

Question 14

Which process can result in a net charge on an object without direct contact with a charged object?

Accepted Answer

Charging by induction

Question 15

A student rubs a glass rod with silk, and the rod becomes positively charged. What has happened at the atomic level?

Accepted Answer

Electrons have been removed from the glass rod.

Question 16

Which of the following is NOT a property of electric charge?

Accepted Answer

Electric charge is created or destroyed in chemical reactions.

Question 17

Two spheres, P and Q, have charges of $+4\ \mathrm{nC}$ and $-2\ \mathrm{nC}$, respectively. They are touched together and then separated. What is the final charge on each sphere?

Accepted Answer

$+1\ \mathrm{nC}$

Question 18

Which of the following statements about polarization is correct?

Accepted Answer

Polarization always results in an attractive force between a charged object and a neutral object.

Question 19

A student touches a charged metal sphere to a neutral metal sphere. What is the result?

Accepted Answer

Charge is transferred by conduction, and both spheres end up with the same type of charge.

Electric Charges and Forces: Charge Model, Conductors & Insulators, and Polarization

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