Question 1

For any circuit the number of independent equations containing emf's, resistances, and currents equals:

Accepted Answer

A)  the number of junctions 
B)  the number of junctions minus 1 
C)  the number of branches 
D)  the number of branches minus 1 
E)  the number of closed loops 
A)  the number of junctions 
B)  the number of junctions minus 1 
C)  the number of branches 
D)  the number of branches minus 1 
E)  the number of closed loops C

Question 2

Resistor 1 has twice the resistance of resistor 2. The two are connected in series and a potential difference is maintained across the combination. The rate of thermal energy dissipation in 1 is:

Accepted Answer

A)  the same as that in 2 
B)  twice that in 2 
C)  half that in 2 
D)  four times that in 2 
E)  one fourth that in 2 
A)  the same as that in 2 
B)  twice that in 2 
C)  half that in 2 
D)  four times that in 2 
E)  one fourth that in 2 B

Question 3

In the diagram R1 > R2 > R3. Rank the three resistors according to the current in them, least to greatest.

Accepted Answer

A)  1, 2, 3 
B)  3, 2, 1 
C)  1, 3, 2 
D)  3, 1, 2 
E)  All are the same 
A)  1, 2, 3 
B)  3, 2, 1 
C)  1, 3, 2 
D)  3, 1, 2 
E)  All are the same E

Question 4

A certain capacitor, in series with a resistor, is being charged. At the end of 10 ms its charge is half the final value. The time constant for the process is about:

Accepted Answer

A)  0.43 ms 
B)  2.3 ms 
C)  6.9 ms 
D)  10 ms 
E)  14 ms 
A)  0.43 ms 
B)  2.3 ms 
C)  6.9 ms 
D)  10 ms 
E)  14 ms

Question 5

If a circuit has L closed loops, B branches, and J junctions the number of independent loop equations is:

Accepted Answer

A)  B - J + 1 
B)  B - J 
C)  B 
D)  L 
E)  L - J 
A)  B - J + 1 
B)  B - J 
C)  B 
D)  L 
E)  L - J

Question 6

A total resistance of 3.0  $\Omega$ is to be produced by combining an unknown resistor R with a 12 $\Omega$ resistor. What is the value of R and how is it to be connected to the 12  $\Omega$ resistor?

Accepted Answer

A)  4.0  $\Omega$, parallel 
B)  4.0  $\Omega$, series 
C)  2.4  $\Omega$, parallel 
D)  2.4  $\Omega$, series 
E)  9.0  $\Omega$, series 
A)  4.0  $\Omega$, parallel 
B)  4.0  $\Omega$, series 
C)  2.4  $\Omega$, parallel 
D)  2.4  $\Omega$, series 
E)  9.0  $\Omega$, series

Question 7

A 3- $\Omega$ and a 1.5- $\Omega$  resistor are wired in parallel and the combination is wired in series to a 4- $\Omega$  resistor and a 10-V emf device. The potential difference across the 3- $\Omega$  resistor is:

Accepted Answer

A)  2.0 V 
B)  6.0 V 
C)  8.0 V 
D)  10 V 
E)  12 V 
A)  2.0 V 
B)  6.0 V 
C)  8.0 V 
D)  10 V 
E)  12 V

Question 8

Two identical batteries, each with an emf of 18 V and an internal resistance of 1  $\Omega$, are wired in parallel by connecting their positive terminals together and connecting their negative terminals together. The combination is then wired across a 4- $\Omega$ resistor. The current in the 4- $\Omega$resistor is:

Accepted Answer

A)  1.0 A 
B)  2.0 A 
C)  4.0 A 
D)  3.6 A 
E)  7.2 A 
A)  1.0 A 
B)  2.0 A 
C)  4.0 A 
D)  3.6 A 
E)  7.2 A

Question 9

In the circuit shown, the capacitor is initially uncharged. At time t = 0, switch S is closed. If  $ \tau $ denotes the time constant, the approximate current through the 3 $\Omega$resistor when t =  $ \tau $/10 is:

Accepted Answer

A)  0.38 A 
B)  0.50 A 
C)  0.75 A 
D)  1.0 A 
E)  1.5 A 
A)  0.38 A 
B)  0.50 A 
C)  0.75 A 
D)  1.0 A 
E)  1.5 A

Question 10

To make a galvanometer into an ammeter, connect:

Accepted Answer

A)  a high resistance in parallel 
B)  a high resistance in series 
C)  a low resistance in series 
D)  a low resistance in parallel 
E)  a source of emf in series 
A)  a high resistance in parallel 
B)  a high resistance in series 
C)  a low resistance in series 
D)  a low resistance in parallel 
E)  a source of emf in series

Question 11

A certain galvanometer has a resistance of 100  $\Omega$ and requires 1 mA for full scale deflection. To make this into a voltmeter reading 1 V full scale, connect a resistance of:

Accepted Answer

A)  1000  $\Omega$ in parallel 
B)  900  $\Omega$ in series 
C)  1000  $\Omega$ in series 
D)  10  $\Omega$ in parallel 
E)  0.1  $\Omega$ in series 
A)  1000  $\Omega$ in parallel 
B)  900  $\Omega$ in series 
C)  1000  $\Omega$ in series 
D)  10  $\Omega$ in parallel 
E)  0.1  $\Omega$ in series

Question 12

Two wires are made of the same material and have the same length but different radii. They are joined end-to-end and a potential difference is maintained across the combination. Of the following the quantity that is the same for both wires is:

Accepted Answer

A)  potential difference 
B)  current 
C)  current density 
D)  electric field 
E)  conduction electron drift speed 
A)  potential difference 
B)  current 
C)  current density 
D)  electric field 
E)  conduction electron drift speed

Question 13

A charged capacitor is being discharged through a resistor. At the end of one time constant the charge has been reduced by (1 - 1/e) = 63% of its initial value. At the end of two time constants the charge has been reduced by what percent of its initial value?

Accepted Answer

A)  82% 
B)  86% 
C)  100% 
D)  between 90% and 100% 
E)  need to know more data to answer the question 
A)  82% 
B)  86% 
C)  100% 
D)  between 90% and 100% 
E)  need to know more data to answer the question

Question 14

The resistance of resistor 1 is twice the resistance of resistor 2. The two are connected in parallel and a potential difference is maintained across the combination. Then:

Accepted Answer

A)  the current in 1 is twice that in 2 
B)  the current in 1 is half that in 2 
C)  the potential difference across 1 is twice that across 2 
D)  the potential difference across 1 is half that across 2 
E)  none of the above are true 
A)  the current in 1 is twice that in 2 
B)  the current in 1 is half that in 2 
C)  the potential difference across 1 is twice that across 2 
D)  the potential difference across 1 is half that across 2 
E)  none of the above are true

Question 15

By using only two resistors, R1 and R2 a student is able to obtain resistances of 3  $\Omega$, 4 $\Omega$, 12 $\Omega$, and 16  $\Omega$. The values of R1 and R2 (in ohms) are:

Accepted Answer

A)  3, 4 
B)  2, 12 
C)  3, 16 
D)  4, 12 
E)  4, 16 
A)  3, 4 
B)  2, 12 
C)  3, 16 
D)  4, 12 
E)  4, 16

Question 16

Nine identical wires, each of diameter d and length L, are connected in series. The combination has the same resistance as a single similar wire of length L but whose diameter is:

Accepted Answer

A)  3d 
B)  9d 
C)  d/3 
D)  d/9 
E)  d/81 
A)  3d 
B)  9d 
C)  d/3 
D)  d/9 
E)  d/81

Question 17

Four 20- $\Omega$  resistors are connected in parallel and the combination is connected to a 20-V emf device. The current in any one of the resistors is:

Accepted Answer

A)  0.25 A 
B)  1.0 A 
C)  4.0 A 
D)  5.0 A 
E)  100 A 
A)  0.25 A 
B)  1.0 A 
C)  4.0 A 
D)  5.0 A 
E)  100 A

Question 18

In the context of the loop and junctions rules for electrical circuits a junction is:

Accepted Answer

A)  where a wire is connected to a resistor 
B)  where a wire is connected to a battery 
C)  where only two wires are joined 
D)  where three or more wires are joined 
E)  where a wire is bent 
A)  where a wire is connected to a resistor 
B)  where a wire is connected to a battery 
C)  where only two wires are joined 
D)  where three or more wires are joined 
E)  where a wire is bent

Question 19

A 120-V power line is protected by a 15-A fuse. What is the maximum number of "120 V, 500 W" light bulbs that can be operated at full brightness from this line?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5 
A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 20

Resistances of 2.0  $\Omega$, 4.0  $\Omega$, and 6.0  $\Omega$ and a 24-V battery are all in series. The current in the 2.0  $\Omega$ resistor is:

Accepted Answer

A)  12 A 
B)  4.0 A 
C)  2.4 A 
D)  2.0 A 
E)  0.50 A 
A)  12 A 
B)  4.0 A 
C)  2.4 A 
D)  2.0 A 
E)  0.50 A

Exam 27: Circuits

For any circuit the number of independent equations containing emf's, resistances, and currents equals:

Resistor 1 has twice the resistance of resistor 2. The two are connected in series and a potential difference is maintained across the combination. The rate of thermal energy dissipation in 1 is:

In the diagram R1 > R2 > R3. Rank the three resistors according to the current in them, least to greatest.

A certain capacitor, in series with a resistor, is being charged. At the end of 10 ms its charge is half the final value. The time constant for the process is about:

If a circuit has L closed loops, B branches, and J junctions the number of independent loop equations is:

A total resistance of 3.0 Ω\OmegaΩ is to be produced by combining an unknown resistor R with a 12 Ω\OmegaΩ resistor. What is the value of R and how is it to be connected to the 12 Ω\OmegaΩ resistor?

A 3- Ω\OmegaΩ and a 1.5- Ω\OmegaΩ resistor are wired in parallel and the combination is wired in series to a 4- Ω\OmegaΩ resistor and a 10-V emf device. The potential difference across the 3- Ω\OmegaΩ resistor is:

In the circuit shown, the capacitor is initially uncharged. At time t = 0, switch S is closed. If τ \tau τ denotes the time constant, the approximate current through the 3 Ω\OmegaΩ resistor when t = τ \tau τ /10 is:

To make a galvanometer into an ammeter, connect:

A certain galvanometer has a resistance of 100 Ω\OmegaΩ and requires 1 mA for full scale deflection. To make this into a voltmeter reading 1 V full scale, connect a resistance of:

Two wires are made of the same material and have the same length but different radii. They are joined end-to-end and a potential difference is maintained across the combination. Of the following the quantity that is the same for both wires is:

A charged capacitor is being discharged through a resistor. At the end of one time constant the charge has been reduced by (1 - 1/e) = 63% of its initial value. At the end of two time constants the charge has been reduced by what percent of its initial value?

The resistance of resistor 1 is twice the resistance of resistor 2. The two are connected in parallel and a potential difference is maintained across the combination. Then:

By using only two resistors, R1 and R2 a student is able to obtain resistances of 3 Ω\OmegaΩ , 4 Ω\OmegaΩ , 12 Ω\OmegaΩ , and 16 Ω\OmegaΩ . The values of R1 and R2 (in ohms) are:

Nine identical wires, each of diameter d and length L, are connected in series. The combination has the same resistance as a single similar wire of length L but whose diameter is:

Four 20- Ω\OmegaΩ resistors are connected in parallel and the combination is connected to a 20-V emf device. The current in any one of the resistors is:

In the context of the loop and junctions rules for electrical circuits a junction is:

A 120-V power line is protected by a 15-A fuse. What is the maximum number of "120 V, 500 W" light bulbs that can be operated at full brightness from this line?

Resistances of 2.0 Ω\OmegaΩ , 4.0 Ω\OmegaΩ , and 6.0 Ω\OmegaΩ and a 24-V battery are all in series. The current in the 2.0 Ω\OmegaΩ resistor is:

Measurement

Motion Along a Straight Line

Vector

Motion in Two and Three Dimensions

Force and Motion I

Force and Motion II

Kinetic Energy and Work

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

Waves I

Waves II

Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Electric Charge

Electric Fields

Gauss Law

Electric Potential

Capacitance

Current and Resistance

Magnetic Fields

Magnetic Fields Due to Currents

Induction and Inductance

Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Nuclear Physics

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

Filters

In the diagram R₁ > R₂ > R₃. Rank the three resistors according to the current in them, least to greatest.

A total resistance of 3.0 $\Omega$ is to be produced by combining an unknown resistor R with a 12 $\Omega$ resistor. What is the value of R and how is it to be connected to the 12 $\Omega$ resistor?

A 3- $\Omega$ and a 1.5- $\Omega$ resistor are wired in parallel and the combination is wired in series to a 4- $\Omega$ resistor and a 10-V emf device. The potential difference across the 3- $\Omega$ resistor is:

A certain galvanometer has a resistance of 100 $\Omega$ and requires 1 mA for full scale deflection. To make this into a voltmeter reading 1 V full scale, connect a resistance of:

By using only two resistors, R₁ and R₂ a student is able to obtain resistances of 3 $\Omega$ , 4 $\Omega$ , 12 $\Omega$ , and 16 $\Omega$ . The values of R₁ and R₂ (in ohms) are:

Four 20- $\Omega$ resistors are connected in parallel and the combination is connected to a 20-V emf device. The current in any one of the resistors is:

Resistances of 2.0 $\Omega$ , 4.0 $\Omega$ , and 6.0 $\Omega$ and a 24-V battery are all in series. The current in the 2.0 $\Omega$ resistor is: