Question 1

Which of the following statements best explains why a spark occurs when you touch a metal doorknob after walking on a carpet on a dry day?

Accepted Answer

Negatively charged electrons are transferred from the carpet to your body, and the spark is the rapid discharge of this built-up charge to the metal doorknob.

Question 2

Which law states that the total electric charge in an isolated system remains constant?

Accepted Answer

Law of Conservation of Charge

Question 3

A plastic rod is rubbed with fur and becomes negatively charged. What happens at the atomic level?

Accepted Answer

Electrons are transferred from the fur to the rod.

Question 4

What is the charge of a single electron?

Accepted Answer

$$-1.602\$$times10^{-19}$$\ \mathrm{C}$$

Question 5

If you want to create a net positive charge of $$10.0\ \mathrm{C} on a$$ $$2.00\ \mathrm{kg}$$ block of copper (atomic number 29, atomic weight $$63.55\ \mathrm{g/mol}$$), what percentage of electrons must be removed? (Avogadro's number $$6.02\$$times10^{23}$$)

Accepted Answer

$$1.4\$$times10^{-7}$$\%$$

Question 6

Which of the following materials is a good electrical conductor?

Accepted Answer

Copper

Question 7

A current of $$5.0\ \mathrm{mA}$$ flows through your skin for $$10.0\ \mathrm{s}. $$How many electrons pass through your skin in this time? (Charge of electron $$e = 1.602\$$times10^{-19}$$\ \mathrm{C})$$

Accepted Answer

$$3.1\$$times10^{17}$$ electrons

Question 8

Which of the following best describes a superconductor?

Accepted Answer

A material that has zero electrical resistance at very low temperatures.

Question 9

Which of the following is a real-world application of superconductors?

Accepted Answer

Magnetic resonance imaging (MRI) machines

Question 10

According to Coulomb’s Law, what happens to the electrostatic force between two point charges if both charges are doubled and the distance between them is also doubled?

Accepted Answer

The force remains the same.

Question 11

Which of the following statements about the quantization of electric charge is correct?

Accepted Answer

Electric charge is always a multiple of the elementary charge $$e.$$

Question 12

Two lightweight metal spheres are suspended near each other from insulating threads. One sphere has a net charge; the other is neutral. What will happen?

Accepted Answer

They will attract each other.

Question 13

Which of the following best describes the process of triboelectric charging?

Accepted Answer

Charging by friction, where electrons are transferred between two materials when rubbed together.

Question 14

What is the magnitude of the electrostatic force between two protons separated by $$2.0\$$times10^{-15}$$\ \mathrm{m}$$? (Use $$e = 1.602\$$times10^{-19}$$\ \mathrm{C}$$, $$k = 8.99\$$times10^{9}$$\ \mathrm{N\cdot m^2$/C^2$$}$)

Accepted Answer

$$58\ \mathrm{N}$$

Question 15

Which of the following is NOT a property of conductors?

Accepted Answer

They have a high resistance to electric current.

Question 16

A laser printer uses electrostatic forces to print. Which step is directly related to the use of electrostatics?

Accepted Answer

Toner is attracted to the areas of the drum that have been discharged by the laser.

Question 17

Which of the following best explains why the electric force is much stronger than the gravitational force between two electrons?

Accepted Answer

The electric force constant $$k is $$much larger than the gravitational constant $$G.$$

Question 18

If you rub a glass rod with silk, what type of charge does the glass rod acquire?

Accepted Answer

Positive

Question 19

Which of the following is a correct statement of Coulomb’s Law for the magnitude of the force between two point charges $$q_1$$ and $$q_2$$ separated by distance $$r$$?

Accepted Answer

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

Electrostatics and Fundamental Forces: Study Notes

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