Question 1

A solid insulating sphere of radius $$a$$ carries a total charge $$Q$$ uniformly distributed throughout its volume. What is the magnitude of the electric field at a distance $$r$$ from the center, where $$r \u003c a$$?

Accepted Answer

$$E = \dfrac{Q r}{4\pi\$$epsilon_0$$ a^3$}$$

Question 2

A long, straight wire has a uniform linear charge density $$\lambda. $$Using Gauss' Law, what is the electric field at a distance $$r$$ from the wire (outside the wire)?

Accepted Answer

$$E = \dfrac{\lambda}{2\pi\$$epsilon_0$$ r}$$

Question 3

A spherical shell of radius $$a$$ carries a uniform surface charge density $$\sigma. $$What is the electric field at a point inside the shell ($$r \u003c a$$)?

Accepted Answer

$$E = 0$$

Question 4

A large, thin, nonconducting sheet has a uniform surface charge density $$\sigma. $$What is the magnitude of the electric field just outside the sheet?

Accepted Answer

$$E = \dfrac{\sigma}{\$$epsilon_0$$}$$

Question 5

A solid conducting sphere is in electrostatic equilibrium. Which of the following statements is true about the electric field inside the conductor?

Accepted Answer

The electric field is zero everywhere inside the conductor.

Question 6

A point charge $$q is $$placed at the center of a spherical conducting shell. The shell is uncharged. What is the induced charge on the inner surface of the shell?

Accepted Answer

$$-q$$

Question 7

Two infinite parallel sheets carry equal but opposite uniform surface charge densities $$+\sigma$$ and $$-\sigma. $$What is the electric field in the region between the sheets?

Accepted Answer

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

Question 8

A long, hollow, conducting cylinder of radius $$a$$ carries a net charge $$Q on $$its surface. What is the electric field at a distance $$r \u003c a$$ from the axis (inside the cylinder)?

Accepted Answer

$$E = 0$$

Question 9

A solid insulating sphere of radius $$a$$ has a uniform charge density $$\rho. $$What is the total charge $$Q$$ contained in the sphere?

Accepted Answer

$$Q = \dfrac{4}{3}\pi a^3$ \rho$$

Question 10

A conducting sphere of radius $$a$$ carries a net charge $$Q. $$What is the electric field just outside the surface of the sphere?

Accepted Answer

$$E = \dfrac{Q}{4\pi\$$epsilon_0$$ a^2$}$$

Question 11

A point charge $$q is $$placed inside a cavity within a neutral conductor. What is the net charge induced on the inner surface of the cavity?

Accepted Answer

$$-q$$

Question 12

A Gaussian surface is chosen to be a cylinder of length $$L$$ and radius $$r$$ coaxial with a long straight wire carrying charge per unit length $$\lambda. $$What is the total electric flux through the surface?

Accepted Answer

$$\Phi_E = \dfrac{\lambda L}{\$$epsilon_0$$}$$

Question 13

Which of the following is a necessary condition for using Gauss' Law to easily calculate the electric field?

Accepted Answer

The charge distribution must have a high degree of symmetry.

Question 14

A solid conducting sphere of radius $$a is $$placed inside a concentric conducting spherical shell with inner radius $$b$$ and outer radius $$c. $$The sphere has charge $$+2Q$$ and the shell has charge $$-Q. $$What is the electric field in the region $$b \u003c r \u003c c ($$inside the shell material)?

Accepted Answer

$$E = 0$$

Question 15

A metallic sphere is placed near a positive point charge. What happens to the charge distribution on the sphere?

Accepted Answer

The side of the sphere closer to the point charge becomes negatively charged, and the far side becomes positively charged.

Question 16

A Gaussian surface encloses both a $$+q$$ and a $$-q$$ point charge. What is the net electric flux through the surface?

Accepted Answer

$$\Phi_E = 0$$

Question 17

A cavity is made inside a conductor in electrostatic equilibrium. What is the electric field inside the cavity if there is no net charge inside the cavity?

Accepted Answer

$$E = 0$$

Question 18

A charged conductor is in electrostatic equilibrium. What is the direction of the electric field just outside the surface?

Accepted Answer

Perpendicular to the surface

Question 19

A solid insulating sphere of radius $$a$$ has a uniform charge density $$\rho. $$What is the electric field at a distance $$r \u003e a$$ from the center?

Accepted Answer

$$E = \dfrac{1}{4\pi\$$epsilon_0$$} \dfrac{Q}{r^2$}$$

Week 2 Lec. 2

Study Guide - Practice Questions

Study Guide - Flashcards