Q: Which of the following is the correct value for the permittivity of free space $$\$$varepsilon_0$$?

$$\$$varepsilon_0$$ = 8.85 \times 10$$^{-12}$$ \ C^2$/(N \cdot m^2$)$$

Question 1

A plastic rod is rubbed with wool, and the rod becomes negatively charged. According to the triboelectric series, what happens during this process?

Accepted Answer

Negative charges are transferred from the wool to the rod.

Question 2

Which of the following materials is most likely to become negatively charged when rubbed with wool, according to the triboelectric series?

Accepted Answer

Teflon

Question 3

Two point charges, $$q_1 = +2$$ \ \mu C$$ and q_2$ = -2 \ \mu C$$, are separated by a distance $$r = 0.5 \ m. $$What is the magnitude of the force between them? Use $$k = 8.99 	imes 10^9$ \ N \cdot m^2$/C^2$.

Accepted Answer

$$F = 0.144 	imes 10^2$ \ N$$

Question 4

Which statement best describes what an electric field represents?

Accepted Answer

A region where an electric force acts on a charge.

Question 5

A charge $$Q$$ creates an electric field at a distance $$r. $$What is the formula for the magnitude of the electric field $$E at $$that point?

Accepted Answer

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

Question 6

If the force between two charges is $$F$$, what will the force be if the distance between them is doubled?

Accepted Answer

$$F/4$$

Question 7

Which of the following best describes a conductor?

Accepted Answer

A material through which charge moves freely.

Question 8

A force of $$3 \ N$$ acts between two charges $$Q$$ and $$Q$$ separated by distance $$r. If $$one charge is changed to $$4Q$$, what is the new force?

Accepted Answer

$$12 \ N$$

Question 9

Which law states that the force between two charges is equal in magnitude and opposite in direction?

Accepted Answer

Newton's 3rd Law

Question 10

Four charges are placed at the corners of a square. What is the direction of the net force on the charge at the lower left corner if all charges are positive?

Accepted Answer

Diagonally away from the center

Question 11

A charge $$q is $$placed in an electric field $$E. $$What is the force $$F$$ experienced by the charge?

Accepted Answer

$$F = qE$$

Question 12

Which of the following is NOT a property of an insulator?

Accepted Answer

Charge moves freely through it.

Question 13

A ball with charge $$+Q$$ and another with $$+4Q$$ are fixed at a distance $$3R$$ apart. Is it possible to place a third charge $$Q_0$$ somewhere on the line between them so that the net force on $$Q_0 is $$zero?

Accepted Answer

Yes, the sign of $$Q_0$$ does not matter.

Question 14

Which of the following best describes the difference between the electric field and the gravitational field?

Accepted Answer

The electric field can be attractive or repulsive, while the gravitational field is always attractive.

Question 15

A point charge $$Q$$ creates an electric field. If the distance from the charge is tripled, what happens to the electric field strength?

Accepted Answer

It becomes 1/9 as strong.

Question 16

Which of the following is a real-world application of the concept of electric fields?

Accepted Answer

The deflection of electron beams in a cathode ray tube.

Question 17

A bee covered in pollen lands on a flower. If the bee and the flower are both slightly charged, what physical law best describes the force between them?

Accepted Answer

Coulomb's Law

Question 18

Which of the following statements about superposition of electric forces is correct?

Accepted Answer

The net force on a charge is the sum of the individual forces from all other charges.

Question 19

Which of the following is the correct value for the permittivity of free space $$\$$varepsilon_0$$?

Accepted Answer

$$\$$varepsilon_0$$ = 8.85 	imes 10$$^{-12}$$ \ C^2$/(N \cdot m^2$)$$

Electric Fields and Forces: Study Guide for PHYS 202 Module 07

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