Q: A +12 nC charge is located at the origin. What is the magnitude of the electric field at a point 5.0 cm away from the charge?

$$4.32 \times 10^4$\ \mathrm{N/C}$$

Question 1

A typical lightning bolt transfers about 15 C of charge to the ground. If each electron carries a charge of $$e = 1.602 	imes 10$$^{-19}$$ C, approximately how many electrons are transferred in a single lightning bolt?

Accepted Answer

$$9.37 	imes 10$$^{19}$$

Question 2

When a glass rod is rubbed with silk, the glass rod becomes positively charged. What happens at the atomic level during this process?

Accepted Answer

Electrons are transferred from the glass to the silk.

Question 3

Two lightweight pith balls, A and B, are hanging straight down and are both neutral. If both are touched with a plastic rod that was rubbed with wool, what will happen to the balls?

Accepted Answer

They will repel each other.

Question 4

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

Accepted Answer

Conductors allow their outermost electrons to become detached and move freely, while insulators have tightly bound electrons.

Question 5

A neutral metal sphere is placed near a negatively charged rod and then grounded. What is the final charge on the sphere after the ground connection and the rod are removed?

Accepted Answer

The sphere is positively charged.

Question 6

Which of the following statements about Coulomb’s Law is correct?

Accepted Answer

The electric force between two charges is inversely proportional to the square of the distance between them.

Question 7

A charged rod is brought near a neutral metal ball. The ball is attracted to the rod. What is the best explanation for this phenomenon?

Accepted Answer

The rod polarizes the metal ball.

Question 8

Which of the following is the correct expression for the magnitude of the electric 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 9

A +12 nC charge is located at the origin. What is the magnitude of the electric field at a point 5.0 cm away from the charge?

Accepted Answer

$$4.32 	imes 10^4$\ \mathrm{N/C}$$

Question 10

Which of the following best describes the concept of charge quantization?

Accepted Answer

Charge is always a multiple of the fundamental unit $$e.$$

Question 11

If two charges $$q_1$$ and $$q_2$$ exert forces on each other, which of the following is true according to Newton’s Third Law?

Accepted Answer

$$F_{1\ on\ 2} = -F_{2\ on\ 1}$$

Question 12

A neutral atom loses one electron. What is the resulting ion called and what is its net charge?

Accepted Answer

Positive ion, $$q = +e$$

Question 13

Which of the following materials is a good conductor of electricity?

Accepted Answer

Copper

Question 14

What is the SI unit of electric charge?

Accepted Answer

Coulomb

Question 15

A charged rod is held near, but does not touch, a neutral electroscope. The leaves of the electroscope spread apart. What is the best explanation for this observation?

Accepted Answer

The rod polarizes the electroscope, causing a separation of charge.

Question 16

Which of the following is the correct formula for the electric field $$\vec{E}$$ produced by a point charge $$q at a $$distance $$r$$?

Accepted Answer

$$\vec{E} = K \frac{q}{r^2$} \hat{r}$$

Question 17

A negatively charged rod is brought near a neutral metal sphere. What happens to the charges in the sphere?

Accepted Answer

Negative charges in the sphere move away from the rod, and positive charges move toward the rod.

Question 18

Which of the following best describes the process of grounding?

Accepted Answer

Connecting an object to the Earth to allow charge to flow.

Question 19

If a plastic rod is rubbed with wool and then brought near small pieces of paper, the paper is attracted to the rod. What is the best explanation for this phenomenon?

Accepted Answer

The rod polarizes the atoms in the paper, creating an attractive force.

Chapter 22: Electric Charges and Forces – Study Notes

Study Guide - Practice Questions

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