Question 1

Which of the following best describes the function of a resistor in an electric circuit?

Accepted Answer

It limits the flow of electric current due to its significant resistance.

Question 2

A battery with an emf of $\varepsilon = 12\ \mathrm{V}$ and internal resistance $r = 0.5\ \Omega$ is connected to a $5.5\ \Omega$ resistor. What is the terminal voltage across the battery?

Accepted Answer

$11.0\ \mathrm{V}$

Question 3

Which law states that the sum of the currents entering a junction equals the sum of the currents leaving the junction?

Accepted Answer

Kirchhoff's Junction Law

Question 4

In a series circuit with two resistors, $R_1 = 4\ \Omega$ and $R_2 = 6\ \Omega$, connected to a $20\ \mathrm{V}$ battery, what is the current through the circuit?

Accepted Answer

$2.0\ \mathrm{A}$

Question 5

Three identical lightbulbs are connected in parallel to a battery. Which of the following is true about the voltage and current in each bulb?

Accepted Answer

Each bulb has the same voltage but different current.

Question 6

A $60\ \mathrm{W}$ lightbulb and a $100\ \mathrm{W}$ lightbulb are both rated for $120\ \mathrm{V}$. Which bulb has the greater resistance?

Accepted Answer

The $60\ \mathrm{W}$ bulb

Question 7

A $400\ \Omega$ resistor has a maximum power rating of $0.800\ \mathrm{W}$. What is the maximum current it can safely carry?

Accepted Answer

$0.0447\ \mathrm{A}$

Question 8

Which of the following best explains why high voltage is used in long-distance power transmission lines?

Accepted Answer

High voltage decreases the current, reducing power loss.

Question 9

A circuit consists of a $12\ \mathrm{V}$ battery, a $2\ \Omega$ resistor, and a $4\ \Omega$ resistor in series. What is the voltage drop across the $4\ \Omega$ resistor?

Accepted Answer

$8\ \mathrm{V}$

Question 10

If a voltmeter is connected in parallel with a resistor in a circuit, what property must the voltmeter have to minimize its effect on the circuit?

Accepted Answer

Very high resistance

Question 11

A $3\ \mathrm{V}$ lithium cell with internal resistance $r = 20\ \Omega$ powers a digital wristwatch that draws $0.3\ \mathrm{mA}$. What is the output (terminal) voltage of the cell?

Accepted Answer

$2.994\ \mathrm{V}$

Question 12

Which of the following statements about power dissipation in a resistor is correct?

Accepted Answer

Power dissipation decreases as resistance increases, if voltage is constant.

Question 13

A circuit contains two resistors, $R_1 = 6\ \Omega$ and $R_2 = 3\ \Omega$, in parallel. What is the equivalent resistance?

Accepted Answer

$2\ \Omega$

Question 14

A battery with emf $\varepsilon$ and internal resistance $r$ is connected to a load resistor $R$. Which equation gives the current in the circuit?

Accepted Answer

$I = \varepsilon / (R + r)$

Question 15

Which instrument is used to measure the current in a circuit, and how should it be connected?

Accepted Answer

An ammeter, connected in series

Question 16

A $120\ \mathrm{V}$ heater draws $8.5\ \mathrm{A}$ of current. What is the power dissipated by the heater?

Accepted Answer

$1.02\ \mathrm{kW}$

Question 17

In a circuit, three identical bulbs are connected as shown: Bulb A is in series with a parallel combination of bulbs B and C. Which bulb is brightest?

Accepted Answer

Bulb A

Question 18

If a switch in a parallel circuit is closed, providing a new path for current, what happens to the total current supplied by the battery?

Accepted Answer

It increases

Question 19

Which of the following is the correct expression for the equivalent resistance $R_{eq}$ of two resistors $R_1$ and $R_2$ in parallel?

Accepted Answer

$R_{eq} = (R_1 R_2)/(R_1 + R_2)$

Question 20

A $10\ \Omega$ resistor and a $20\ \Omega$ resistor are connected in series to a $30\ \mathrm{V}$ battery. What is the voltage drop across the $20\ \Omega$ resistor?

Accepted Answer

$20\ \mathrm{V}$

Electric Circuits: Fundamentals, Laws, and Applications

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