Q: What is the magnitude of the electric force between two charges, $$q_1 = 2.0$$ \times $$10^{-6}$$\ \mathrm{C}$$ and q_2$ = -2.0 \times 10$$^{-6}$$\ \mathrm{C}$$, separated by $$4\ \mathrm{m} in $$vacuum? Use $$k = 9.0 \times 10^9$\ \mathrm{N\,m^2$/C^2$$}$.

$$F = 2.25 \times 10$$^{-3}$$\ \mathrm{N}$$

Question 1

Which of the following statements best describes the conservation of electric charge?

Accepted Answer

Electric charge is conserved; it can only be transferred from one object to another.

Question 2

A proton and an electron are placed 1 meter apart in vacuum. What is the direction of the electric force on the electron due to the proton?

Accepted Answer

The force is attractive and points toward the proton.

Question 3

What is the magnitude of the electric force between two charges, $$q_1 = 2.0$$ 	imes $$10^{-6}$$\ \mathrm{C}$$ and q_2$ = -2.0 	imes 10$$^{-6}$$\ \mathrm{C}$$, separated by $$4\ \mathrm{m} in $$vacuum? Use $$k = 9.0 	imes 10^9$\ \mathrm{N\,m^2$/C^2$$}$.

Accepted Answer

$$F = 2.25 	imes 10$$^{-3}$$\ \mathrm{N}$$

Question 4

Which equation correctly expresses Coulomb’s Law for the magnitude of the force between two point charges?

Accepted Answer

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

Question 5

A bee detects the electric field of a flower. If the flower has a net negative charge and the bee has a net positive charge, what is the direction of the electric force on the bee as it approaches the flower?

Accepted Answer

The force is attractive and points toward the flower.

Question 6

Which of the following best describes the direction of electric field lines around a single positive point charge?

Accepted Answer

They radiate outward from the charge.

Question 7

Given two equal positive charges at $$(0, 1) m $$and $$(0, -1) m$$, what is the direction of the net electric force on a third positive charge at $$(1, 0) m$$?

Accepted Answer

Along the positive $$x-$$axis

Question 8

Which of the following is a correct expression for the electric field $$\vec{E}$$ created by a point charge $$Q at a $$distance $$r$$?

Accepted Answer

$$\vec{E} = k \dfrac{Q}{r^2$} \hat{r}$$

Question 9

A shark uses special organs to detect the electric fields generated by prey. Which physical principle allows the shark to sense these fields?

Accepted Answer

Electric fields extend through space and can exert forces on charges at a distance.

Question 10

If a test charge $$q$$ experiences a force $$\vec{F} in an $$electric field $$\vec{E}$$, which equation relates these quantities?

Accepted Answer

$$\vec{F} = q \vec{E}$$

Question 11

Which of the following is NOT a property of electric field lines?

Accepted Answer

Field lines can cross each other.

Question 12

A metal sphere is charged by contact with a negatively charged ebonite rod. What happens to the sphere’s charge?

Accepted Answer

The sphere gains electrons and becomes negatively charged.

Question 13

Two charges, $$q_1 = +2.0$$\ \mu\mathrm{C}$$ at (0$$, 1)$$ m and q_2$ = -2.0\ \mu\mathrm{C} at$$ $$(0, -1) m$$, are placed in the $$xy-$$plane. What is the direction of the electric field at $$(1, 0) m$$?

Accepted Answer

Along the positive $$y-$$axis

Question 14

Which of the following best explains why the electric force between two charges decreases as the distance between them increases?

Accepted Answer

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

Question 15

A flower emits a negative electric field and a bee emits a positive electric field. What happens when the bee approaches the flower?

Accepted Answer

The bee is attracted to the flower due to the electric field.

Question 16

Which of the following is a vector quantity?

Accepted Answer

Electric field

Question 17

If the $$x- $$and $$y-$$components of a vector are $$A_x = 3$$ and $$A_y = 4$$, what is the magnitude of the vector?

Accepted Answer

$$A = 5$$

Question 18

Which of the following is true about the electric field at a point in space?

Accepted Answer

It is defined as the force per unit charge at that point.

Question 19

A test charge is placed in a region where the electric field is zero. What force does it experience?

Accepted Answer

Zero force

Coulomb’s Law and Electric Fields: Physics with Calculus Study Guide

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