Question 1

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

Accepted Answer

Radially outward from the charge

Question 2

A charged rod of length $$L$$ has a total charge $$Q$$ uniformly distributed along its length. What is the linear charge density $$\lambda of $$the rod?

Accepted Answer

$$\lambda = \dfrac{Q}{L}$$

Question 3

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

Accepted Answer

Field lines begin on negative charges and end on positive charges.

Question 4

A point charge $$q is $$placed at the origin. What is the magnitude of the electric field at a distance $$r$$ from the charge?

Accepted Answer

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

Question 5

Two point charges, $$+2q$$ and $$-q$$, are placed a fixed distance apart. How does the number of electric field lines leaving the $$+2q$$ charge compare to those ending on the $$-q$$ charge?

Accepted Answer

Twice as many lines leave $$+2q as $$end on $$-q$$

Question 6

What is the net electric field at the midpoint between two equal positive point charges separated by a distance $$d$$?

Accepted Answer

Zero, because the fields cancel each other

Question 7

A very long, thin rod has a uniform linear charge density $$\lambda. $$What is the magnitude of the electric field at a distance $$r$$ from the rod?

Accepted Answer

$$E = \dfrac{2k\lambda}{r}$$

Question 8

Which of the following actions will increase the electric field strength at a fixed point near a uniformly charged rod?

Accepted Answer

Make the rod shorter without changing the charge

Question 9

A parallel-plate capacitor consists of two plates of area $$A$$ separated by distance $$d$$, with charge $$+Q$$ and $$-Q on $$the plates. What is the magnitude of the electric field between the plates?

Accepted Answer

$$E = \dfrac{Q}{\$$epsilon_0$$ A}$$

Question 10

The electric field of an infinite plane of charge with surface charge density $$\eta is$$:

Accepted Answer

$$E = \dfrac{\eta}{2\$$epsilon_0$$}$$

Question 11

A proton is released from rest in a uniform electric field. Which of the following best describes its motion?

Accepted Answer

It accelerates in the direction of the electric field

Question 12

A charged particle of mass $$m$$ and charge $$q is $$placed in a uniform electric field $$\vec{E}. $$What is its acceleration?

Accepted Answer

$$a = \dfrac{qE}{m}$$

Question 13

A dipole consists of charges $$+q$$ and $$-q$$ separated by distance $$s. $$What is the magnitude of its dipole moment?

Accepted Answer

$$p = qs$$

Question 14

What is the torque $$	au on an $$electric dipole with moment $$\vec{p} in a $$uniform electric field $$\vec{E} at $$angle $$	heta$$?

Accepted Answer

$$	au = pE \sin	heta$$

Question 15

A sphere of charge $$Q$$ and radius $$R$$ produces an electric field outside the sphere that is:

Accepted Answer

Identical to that of a point charge $$Q at $$the center

Question 16

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

Accepted Answer

A parallel plate capacitor

Question 17

If a charge $$Q is $$uniformly distributed over a surface area $$A$$, what is the surface charge density $$\eta$$?

Accepted Answer

$$\eta = \dfrac{Q}{A}$$

Question 18

A charged disk of radius $$R$$ and surface charge density $$\eta$$ produces an on-axis electric field at distance $$z$$ from its center given by:

Accepted Answer

$$E = \dfrac{\eta}{2\$$epsilon_0$$} \left[1 - \dfrac{z}{\sqrt{z^2$ + R^2$}}\right]$$

Question 19

Which of the following best explains why the electric field inside a parallel-plate capacitor is uniform?

Accepted Answer

The plates are large and parallel, so edge effects are negligible

Chapter 23: The Electric Field – Structured Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards