Question 1

Which of the following best describes how a long-range electric force is transmitted from one charge to another?

Accepted Answer

By the creation of an electric field by one charge, which then exerts a force on another charge.

Question 2

Which of the following statements about the electric field is correct?

Accepted Answer

The electric field is present at all points in space and is a vector.

Question 3

A charged particle in an electric field experiences a force given by which equation?

Accepted Answer

$$F = qE$$

Question 4

What are the SI units of the electric field?

Accepted Answer

Newtons per coulomb (N/C)

Question 5

Which of the following is true about the direction of the electric field created by a positive point charge?

Accepted Answer

It points away from the charge.

Question 6

If the electric field at a point is $$E$$ and a particle with charge $$q is $$placed at that point, what is the force on the particle?

Accepted Answer

$$F = qE$$

Question 7

The electric field at a distance $$r$$ from a point charge $$q is $$given by which formula?

Accepted Answer

$$E = \frac{q}{4\pi\$$epsilon_0$$ r^2$}$$

Question 8

Which of the following best describes the electric field lines for a negative point charge?

Accepted Answer

They point inward toward the charge.

Question 9

A singly charged calcium ion ($$q = +e) is in a $$cell membrane with an electric field strength of $$1.0 	imes 10^7$ N/C. What is the magnitude of the electric force on the ion? (e = 1.6$$ 	imes $$10^{-19} C)$$

Accepted Answer

$$1.6 	imes 10$$^{-12}$$ N$

Question 10

Which device provides a practical way to produce a uniform electric field?

Accepted Answer

A parallel-plate capacitor

Question 11

What is the principle of superposition as it applies to electric fields?

Accepted Answer

The net electric field is the vector sum of the fields due to each charge.

Question 12

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

Accepted Answer

They form closed loops around a single charge.

Question 13

If two equal but opposite charges are separated by a small distance, what is formed?

Accepted Answer

An electric dipole

Question 14

Which of the following best describes the units of a unit vector?

Accepted Answer

The unit vector has no units.

Question 15

A proton in a hydrogen atom orbits at a radius of $$0.053 nm. $$What is the electric field strength at this distance due to the proton? (Use $$e = 1.6 	imes 10$$^{-19}$$ C, $$\$$epsilon_0 = 8.85$$ 	imes $$10^{-12} C$^2/N$$·m$$^2)$$

Accepted Answer

$$E = \frac{e}{4\pi\$$epsilon_0$$ r^2$}$$

Question 16

Which of the following is a correct statement about the force on a positive charge in an electric field?

Accepted Answer

It is in the direction of the electric field.

Question 17

If the electric field at point A is stronger than at point B, what can you infer about their distances from the source charge?

Accepted Answer

Point A is closer to the source charge than point B.

Question 18

Which of the following is a vector quantity?

Accepted Answer

Electric field

Question 19

Which of the following is the correct formula for the net electric field due to multiple point charges?

Accepted Answer

$$\vec{E}_{net} = \sum \vec{E}_i$$

Electric Fields: Concepts, Models, and Applications

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