Q: In the Bohr model of the hydrogen atom, the electron orbits the proton at a radius of $$5.29 \times 10$$^{-11}$$\ \mathrm{m}. If $$the magnitude of the force is $$8.22 \times 10$$^{-8}$$\ \mathrm{N}$$, what is the speed of the electron? ($$m_e = 9.11 \times 10$$^{-31}$$\ \mathrm{kg})$$

$$2.18 \times 10^6$\ \mathrm{m/s}$$

Question 1

Which of the following statements best describes the Law of Conservation of Electric Charge?

Accepted Answer

The net electric charge of an isolated system remains constant during any process.

Question 2

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 3

Which of the following materials is classified as a semiconductor?

Accepted Answer

Silicon

Question 4

How many electrons are there in one coulomb of negative charge? Use $$e = 1.60 	imes 10$$^{-19}$$\ \mathrm{C}.$$

Accepted Answer

$$6.25 	imes 10$$^{18}$$

Question 5

Which equation correctly expresses the relationship between charge, number of electrons, and elementary charge?

Accepted Answer

$$q = Ne$$

Question 6

A negatively charged ebonite rod is brought near a neutral metal sphere without touching it. What is the process called when the sphere becomes charged after being grounded?

Accepted Answer

Charging by induction

Question 7

Which of the following best describes the force between two point charges according to Coulomb’s Law?

Accepted Answer

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

Question 8

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

Accepted Answer

It becomes one-fourth as large.

Question 9

In the Bohr model of the hydrogen atom, the electron orbits the proton at a radius of $$5.29 	imes 10$$^{-11}$$\ \mathrm{m}. If $$the magnitude of the force is $$8.22 	imes 10$$^{-8}$$\ \mathrm{N}$$, what is the speed of the electron? ($$m_e = 9.11 	imes 10$$^{-31}$$\ \mathrm{kg})$$

Accepted Answer

$$2.18 	imes 10^6$\ \mathrm{m/s}$$

Question 10

Which of the following is NOT a property of electrical conductors?

Accepted Answer

They do not allow electric charge to move freely.

Question 11

A gold-leaf electroscope is used to detect electric charge. What happens to the leaves when a charged rod is brought near the top plate without touching it?

Accepted Answer

The leaves repel each other due to induced charge separation.

Question 12

Which of the following best explains why plastic is considered an electrical insulator?

Accepted Answer

It does not allow electric charge to move freely.

Question 13

Three point charges are placed on a line: $$q_2 = -4.0$$\ \mu\mathrm{C}$$, q_1$ = +3.0\ \mu\mathrm{C}$$, $$q_3 = -7.0$$\ \mu\mathrm{C}$$, with q_1$ between q_2$ and q_3$. If q_2$ is 0.20$$\ \mathrm{m}$$ from q_1$ and q_3$ is 0.15$$\ \mathrm{m}$$ from q_1$, what is the net force on q_1$? (k = 8.99$$ 	imes $$10^9$$\ \mathrm{N} \cdot \mathrm{m}^2/\mathrm{C}^2$$)

Accepted Answer

$$+5.7\ \mathrm{N}$$

Question 14

Which of the following is true about the forces between two point charges according to Newton’s Third Law?

Accepted Answer

The forces are equal in magnitude and opposite in direction.

Question 15

A negatively charged rod is brought near a neutral plastic object. What happens at the molecular level?

Accepted Answer

The molecules in the plastic become polarized, with positive charges attracted toward the rod.

Question 16

Which of the following is the correct value for the elementary charge $$e$$?

Accepted Answer

$$1.60 	imes 10$$^{-19}$$\ \mathrm{C}$$

Question 17

Which of the following best describes charging by contact?

Accepted Answer

A charged object touches a neutral object, transferring charge.

Question 18

Which of the following is the correct expression for the Coulomb constant $$k in $$terms of the permittivity of free space $$\$$varepsilon_0$$?

Accepted Answer

$$k = \frac{1}{4 \pi \$$varepsilon_0$$}$$

Electric Charge and Coulomb’s Law – Physics 1201 Study Notes

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