Q: A point charge $$q = +15\ \mu\mathrm{C} is $$placed in a vacuum. What is the electric field at a distance $$0.20\ \mathrm{m}$$ from the charge?

$$\E$$ = \frac{(8.99 \times $$10^9) (15$$ \times $$10^{-6}$$)}{$$(0.20)^2$$}\ =\ 3.4 \times $$10^6$$\ \mathrm{N/C}$$\$$

Question 1

Which of the following best describes the direction of the electric field produced by a positive point charge?

Accepted Answer

The electric field points radially outward away from the charge.

Question 2

A test charge $$q_0$$ experiences a force $$\vec{F} at a $$point in space. What is the electric field $$\vec{E} at $$that point?

Accepted Answer

$$\$$\vec{E} = \frac{\vec{F}}{$$q_0$$}$$\$$

Question 3

Two point charges, $$q_1 = +16$$\ \mu\mathrm{C}$$ and q_2$ = +4.0\ \mu\mathrm{C}$$, are separated by $$3.0\ \mathrm{m}. At $$what distance from $$q_1$$ along the line joining them is the net electric field zero?

Accepted Answer

$$\d = 2.0$$\ \mathrm{m}$$\$$

Question 4

What is the electric field at a distance $$r$$ from a point charge $$q$$?

Accepted Answer

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

Question 5

A parallel plate capacitor has a charge $$q on $$its plates, area $$A$$, and the permittivity of free space $$\$$varepsilon_0$$. What is the magnitude of the electric field between the plates?

Accepted Answer

$$\E$$ = \frac{q}{\$$varepsilon_0 A$$}$$\$$

Question 6

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

Accepted Answer

Electric field lines can cross each other.

Question 7

A positive test charge is placed in a uniform electric field. What is the direction of the force on the test charge?

Accepted Answer

In the direction of the electric field.

Question 8

At equilibrium under electrostatic conditions, what is true about the electric field inside a conductor?

Accepted Answer

It is zero everywhere inside the conductor.

Question 9

A test charge of $$3.0 	imes 10$$^{-6}$$\ \mathrm{C}$$ experiences a force of $$6.0 	imes 10$$^{-6}$$\ \mathrm{N} in an $$electric field. What is the magnitude of the electric field?

Accepted Answer

$$\2.0$$\ \mathrm{N/C}$$\$$

Question 10

Which of the following is a correct statement about the electric field produced by multiple charges?

Accepted Answer

The electric field at a point is the vector sum of the fields due to each charge.

Question 11

A charge $$q is $$placed at the center of a hollow, electrically neutral, spherical conductor. What is the induced charge on the inner and outer surfaces?

Accepted Answer

Inner: $$-q$$, Outer: $$+q$$

Question 12

Which of the following best explains why a conductor shields its interior from external electric fields?

Accepted Answer

The charges inside the conductor move to the surface, canceling the internal field.

Question 13

A point charge $$q = +15\ \mu\mathrm{C} is $$placed in a vacuum. What is the electric field at a distance $$0.20\ \mathrm{m}$$ from the charge?

Accepted Answer

$$\E$$ = \frac{(8.99 	imes $$10^9) (15$$ 	imes $$10^{-6}$$)}{$$(0.20)^2$$}\ =\ 3.4 	imes $$10^6$$\ \mathrm{N/C}$$\$$

Question 14

Which of the following is TRUE about the electric field between the plates of a parallel plate capacitor (ignoring edge effects)?

Accepted Answer

The electric field is uniform between the plates.

Question 15

If the force on a charge $$q in an $$electric field $$E is$$ $$F$$, which equation is correct?

Accepted Answer

$$\F = qE$\$$

Question 16

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

Accepted Answer

They form closed loops around isolated charges.

Question 17

A positive test charge is placed at the center of a square formed by four identical negative charges at the corners. What is the net force on the test charge?

Accepted Answer

The net force is zero due to symmetry.

Question 18

Which of the following best describes the relationship between the number of electric field lines and the magnitude of the charge?

Accepted Answer

The number of lines is proportional to the magnitude of the charge.

Chapter 16: Electric Fields – Concepts, Calculations, and Applications

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