Question 1

Which of the following statements best describes the electric field inside a conductor in electrostatic equilibrium?

Accepted Answer

The electric field is zero everywhere inside the conductor.

Question 2

A Faraday cage is used to protect sensitive electronic equipment from external electric fields. Which property of conductors explains this phenomenon?

Accepted Answer

The electric field inside a conductor is zero in electrostatic equilibrium.

Question 3

What is the magnitude of the electric field just outside the surface of a conductor in electrostatic equilibrium, given a surface charge density $$\sigma$$?

Accepted Answer

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

Question 4

If a hollow conducting shell is placed in an external electric field, what happens to the electric field inside the cavity?

Accepted Answer

It is zero due to the rearrangement of free electrons.

Question 5

A charged conductor has an irregular shape. Where is the surface charge density $$\sigma$$ the greatest?

Accepted Answer

Where the radius of curvature is smallest.

Question 6

Which of the following is NOT a property of conductors in electrostatic equilibrium?

Accepted Answer

The electric field just outside the conductor is parallel to the surface.

Question 7

A spherical conductor of radius $$R$$ carries a net charge $$-Q. $$What is the electric field at a distance $$r \u003e R$$ from the center?

Accepted Answer

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

Question 8

Why do power line technicians wear conductive suits when working near high-voltage lines?

Accepted Answer

To ensure that any external electric field does not penetrate their bodies, acting as a Faraday cage.

Question 9

A hollow conductor contains a point charge $$+q at $$its center. What is the net charge induced on the inner surface of the conductor?

Accepted Answer

$$-q$$

Question 10

Which equation correctly expresses Gauss’s Law for electric flux $$\Phi_E$$ through a closed surface?

Accepted Answer

$$\Phi_E = \frac{Q_{enclosed}}{\$$epsilon_0$$}$$

Question 11

A cable is shielded with a conducting layer. What is the main purpose of this shielding?

Accepted Answer

To block external electric fields from affecting the signals inside the cable.

Question 12

If a conductor is placed in an external electric field, what happens to the free electrons in the conductor?

Accepted Answer

They rearrange themselves on the surface to cancel the internal field.

Question 13

A conducting sphere of radius $$R is $$given a net charge $$Q. $$What is the electric field inside the sphere ($$r \u003c R$$)?

Accepted Answer

$$E = 0$$

Question 14

Which of the following best explains why the electric field just outside a conductor is perpendicular to the surface?

Accepted Answer

Because any parallel component would cause charges to move, violating electrostatic equilibrium.

Question 15

A tin foil hat is sometimes humorously claimed to block mind control signals. Physically, what principle is this based on?

Accepted Answer

The hat acts as a Faraday cage, blocking external electric fields.

Question 16

If the total charge on a conductor is $$Q$$ and its surface area is $$A$$, what is the surface charge density $$\sigma$$?

Accepted Answer

$$\sigma = \frac{Q}{A}$$

Question 17

Which of the following real-world applications does NOT rely on the properties of conductors in electrostatic equilibrium?

Accepted Answer

Using insulators to prevent current flow.

Question 18

A Gaussian surface is drawn just inside a conductor in electrostatic equilibrium. What is the net electric flux through this surface?

Accepted Answer

Zero, because the electric field inside is zero.

Question 19

Which of the following best describes the distribution of excess charge on a conductor in electrostatic equilibrium?

Accepted Answer

It resides entirely on the surface.

Conductors in Electrostatic Equilibrium and Applications of Gauss's Law

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