Question 1

Which of the following best describes the conventional direction of electric current in a circuit?

Accepted Answer

From positive to negative terminal

Question 2

A copper wire has a cross-sectional area $$A$$ and length $$L. If $$the resistivity of copper is $$\rho$$, what is the resistance $$R of $$the wire?

Accepted Answer

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

Question 3

Which material is most likely to have no free charge carriers under normal conditions?

Accepted Answer

Glass

Question 4

The drift velocity $$v_d of $$electrons in a conductor is best described as:

Accepted Answer

The small net velocity of electrons due to the applied electric field

Question 5

Which equation correctly relates current $$I to $$the number density of charge carriers $$n$$, charge $$q$$, cross-sectional area $$A$$, and drift velocity $$v_d$$?

Accepted Answer

$$I = nqAv_d$$

Question 6

A resistor obeys Ohm’s Law if:

Accepted Answer

The current through it is proportional to the voltage across it

Question 7

Which of the following is a correct unit for resistivity?

Accepted Answer

$$\Omega \cdot m$$

Question 8

If the current in a wire is $$2\ \mathrm{A}$$, how much charge passes through a cross-section in $$10\ \mathrm{s}$$?

Accepted Answer

$$20\ \mathrm{C}$$

Question 9

Which of the following statements about semiconductors is correct?

Accepted Answer

Their conductivity can be controlled

Question 10

A device is found to have a non-linear $$V$$-$$I$$ characteristic. Which of the following is most likely true?

Accepted Answer

It is a non-ohmic device

Question 11

If the length of a wire is doubled and its cross-sectional area is halved, how does its resistance change?

Accepted Answer

It becomes four times larger

Question 12

Which of the following best explains why the signal in a wire propagates much faster than the drift velocity of electrons?

Accepted Answer

The electric field propagates rapidly through the conductor

Question 13

A current of $$0.5\ \mathrm{A}$$ flows through a resistor of $$10\ \Omega. $$What is the voltage across the resistor?

Accepted Answer

$$5\ \mathrm{V}$$

Question 14

Which of the following is NOT a property of conductors?

Accepted Answer

They have high resistivity

Question 15

If a material has a resistivity $$\rho$$ that increases with temperature, what type of material is it most likely to be?

Accepted Answer

A conductor

Question 16

Which of the following equations correctly expresses Ohm’s Law?

Accepted Answer

$$V = IR$$

Question 17

A glass rod is used in an electrical experiment. Which statement is most accurate?

Accepted Answer

It is an insulator

Question 18

Which of the following best describes the relationship between resistance and resistivity?

Accepted Answer

Resistance depends on both material and geometry, resistivity is a material property

Question 19

A wire has resistance $$R. If $$its length is tripled and its cross-sectional area is doubled, what is the new resistance?

Accepted Answer

$$\dfrac{3}{2}R$$

Question 20

Which of the following is a correct statement about Ohmic and non-Ohmic devices?

Accepted Answer

Ohmic devices have a constant resistance, non-Ohmic devices do not

Electric Current and DC Circuit Analysis

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