Question 1

A flashlight uses two 1.5 V batteries in series. What is the total potential difference provided to the circuit?

Accepted Answer

$$3.0\ \mathrm{V}$$

Question 2

Which of the following best describes the direction of conventional current in a metal wire?

Accepted Answer

It is in the direction that positive charges would move.

Question 3

A copper wire has a length $$L$$ and cross-sectional area $$A. $$Its resistance $$R is $$given by:

Accepted Answer

$$R = \rho \dfrac{L}{A}$$

Question 4

Which of the following statements about the motion of electrons in a conductor at electrostatic equilibrium is correct?

Accepted Answer

Electrons have zero average velocity.

Question 5

If a wire is connected across a battery and a steady current flows, what is the primary cause of energy loss in the wire?

Accepted Answer

Energy is lost through collisions of electrons with atoms (resistance).

Question 6

The drift velocity $$v_d of $$electrons in a wire is given by $$v_d = \dfrac{e	au}{m_e}E. $$What does $$	au$$ represent?

Accepted Answer

The average time between collisions for an electron.

Question 7

A metal wire is connected to a battery. What happens to the distribution of charge along the wire immediately after connection?

Accepted Answer

A nonuniform charge distribution is established, creating an internal electric field.

Question 8

Which equation correctly relates current $$I$$, potential difference $$V$$, and resistance $$R$$ for an ohmic material?

Accepted Answer

$$V = IR$$

Question 9

If the resistivity $$\rho of a $$material increases, what happens to the resistance $$R of a $$wire made from that material, assuming length and area are constant?

Accepted Answer

Resistance increases.

Question 10

A book slides across a table at constant speed when pushed. This is analogous to which aspect of electron motion in a wire?

Accepted Answer

A steady electric field is needed to keep electrons moving at constant drift speed due to collisions (resistance).

Question 11

Which of the following best describes the physical meaning of Ohm’s Law for a metal wire?

Accepted Answer

The current is directly proportional to the applied voltage, provided the temperature is constant.

Question 12

If the cross-sectional area $$A of a $$wire is doubled while keeping its length $$L$$ and resistivity $$\rho$$ constant, what happens to its resistance $$R$$?

Accepted Answer

Resistance is halved.

Question 13

Which of the following is true about the electric field inside a conductor in electrostatic equilibrium?

Accepted Answer

The electric field is zero everywhere inside the conductor.

Question 14

A wire of length $$L$$ and area $$A is $$made of a material with conductivity $$\sigma. $$What is the resistance $$R of $$the wire?

Accepted Answer

$$R = \dfrac{1}{\sigma} \dfrac{L}{A}$$

Question 15

Which of the following best explains why a battery can maintain a steady current in a circuit?

Accepted Answer

It continuously supplies a potential difference, pushing electrons through the circuit.

Question 16

If a wire is cut, what happens to the electric field inside the wire?

Accepted Answer

The electric field becomes zero everywhere inside the wire.

Question 17

Which of the following is a correct statement about the relationship between resistivity $$\rho$$ and conductivity $$\sigma$$?

Accepted Answer

$$\rho = \dfrac{1}{\sigma}$$

Question 18

A copper wire and an aluminum wire have the same length and cross-sectional area. If the resistivity of copper is less than that of aluminum, which wire has the lower resistance?

Accepted Answer

The copper wire.

Question 19

Which of the following best describes the motion of electrons in a conductor when an electric field is applied?

Accepted Answer

Electrons undergo random thermal motion with a net drift opposite to the electric field.

Current and Resistance: Fundamentals of Electric Circuits

Study Guide - Practice Questions

Study Guide - Flashcards