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

$$e = 1.60 \times 10$$^{-19}$$\ \mathrm{C}$$

Question 1

Which of the following statements best explains why lightning, as shown in the image, occurs during a thunderstorm?

Accepted Answer

Lightning occurs because clouds and the ground develop opposite charges, and the electric field between them becomes strong enough to ionize the air, allowing charge to flow.

Question 2

Which of the following best describes the force between two objects with like charges, as shown in the second image?

Accepted Answer

The force is repulsive and acts to push the objects away from each other.

Question 3

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

Accepted Answer

The fur becomes positively charged because it loses electrons to the rod.

Question 4

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

Accepted Answer

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

Question 5

A neutral object is attracted to a charged object due to induced polarization. The neutral object must be:

Accepted Answer

Either a conductor or an insulator

Question 6

Which of the following statements about electric charge is correct?

Accepted Answer

Electric charge is conserved; it can move from one place to another, but the total amount remains the same.

Question 7

A positively charged rod is brought near, but does not touch, a negatively charged electroscope (see image 3). What happens to the foil leaves?

Accepted Answer

The leaves move closer together.

Question 8

Which of the following is the correct formula for the magnitude of the electric field $$E$$ due to a point charge $$Q at a $$distance $$r$$?

Accepted Answer

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

Question 9

Two point charges, $$q_1 = -2.5$$ 	imes $$10^{-6}$$\ \mathrm{C}$$ and q_2$ = 6 	imes 10$$^{-6}$$\ \mathrm{C}$$, are placed 1.0 m apart on the x-axis. Where is the electric field zero?

Accepted Answer

Somewhere to the left of $$q_1$$

Question 10

Which of the following is the correct expression for the electrostatic force between two point charges $$q_1$$ and $$q_2$$ separated by a distance $$r$$?

Accepted Answer

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

Question 11

A charged object with charge $$q is $$placed in a uniform electric field $$E. $$What is the force on the object?

Accepted Answer

$$F = Eq$$

Question 12

A negatively charged electron enters a region where a uniform electric field is directed vertically upward. What is the direction of the force on the electron?

Accepted Answer

Downward

Question 13

A metal sphere with charge $$q_1 is $$placed near another metal sphere with charge $$q_2 = 3q_1$. According to Coulomb's law, how do the magnitudes of the forces on each sphere compare?

Accepted Answer

The forces are equal in magnitude and opposite in direction.

Question 14

A particle with charge $$q = -1.6 	imes 10$$^{-19}$$\ \mathrm{C}$$ and mass $$m = 9.11 	imes 10$$^{-31}$$\ \mathrm{kg}$$ enters a uniform electric field $$E = 6.8\ \mathrm{N/C}. $$What is the magnitude of its acceleration?

Accepted Answer

$$a = \frac{Eq}{m} = \frac{(6.8)(1.6 	imes 10$$^{-19}$$)}{9.11 	imes 10$$^{-31}$$} = 1.2 	imes 10$$^{12}$$\ \mathrm{m/s^2$}$$

Question 15

Which of the following materials is a good conductor of electricity?

Accepted Answer

Copper

Question 16

A neutral object is attracted to a charged rod. Which of the following best explains this phenomenon?

Accepted Answer

The neutral object is polarized, and the induced charges create an attractive force.

Question 17

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

Accepted Answer

Electric field lines point away from positive charges and toward negative charges.

Question 18

If two identical metal spheres are touched together and then separated, what can be said about their charges?

Accepted Answer

They will have equal charges.

Question 19

Which of the following is true about the electric field at a point exactly midway between two equal but opposite charges?

Accepted Answer

The electric field is the vector sum of the fields from both charges and points from the positive to the negative charge.

CH 16

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