WebAssign Girish Pathangey PHY131 Test #4 Fall2012 (Test ...docshare04.docshare.tips/files/20690/206900359.pdf · Girish Pathangey PHY 131 Fall 2012, Fall 2012 Instructor: Ricardo

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012

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1. 1/1 points | Previous Answers

At what frequency will a 50-mH inductor have a reactance of 750 Ω?


For the circuit shown below, in the branch of the circuit containing the capacitor and the ammeter, the resistance is small enough to

ignore. Also, the inductance in each of the branches is small enough to ignore.

Assume that RA = 2.0 Ω, C = 2.0 μH, RB = 4.0 Ω, and VB = 12.0 V. Assume that the switch S is suddenly closed after having

PHY131-Test #4-Fall2012 (Test)

Girish Pathangey

PHY-131 Fall 2012, Fall 2012

Instructor: Ricardo Alarcon

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2.39 kHz

4.24 mHz

15.0 kHz

94.2 kHz

4.24 Hz

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012


been open for a long time. Immediately after closing the switch, what will be the amount of current passing through the ammeter?

6.00 A

zero

9.00 A

2.00 A

3.60 A

4.00 A

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012



The inductor shown in the figure below is a part of a complete circuit;; the rest of the circuit is not shown. For all parts of thisquestion, you are given that the electric potential at location A is higher than the electric potential at location B.

(a) Consider the possibility that the current through this inductor is from A to B. Recall that the potential is higher at location A.Which of the following statements is most accurate?

(b) Consider the possibility that the current through this inductor is from B to A. Recall that the potential is higher at location A. Which of the followingstatements is most accurate?

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The amount of current must be increasing. The amount of current must be decreasing. The amount of currentmay either be steady or increasing, but not decreasing. The amount of current may either be steady or decreasing, but notincreasing. The amount of current may either be steady, increasing, or decreasing. If the potential is higher at A, then it isnot possible for the current to be flowing from A to B.

The amount of current must be increasing. The amount of current must be decreasing. The amount of current may either be steady or

increasing, but not decreasing. The amount of current may either be steady or decreasing, but not increasing. The amount of current may either

be steady, increasing, or decreasing. If the potential is higher at A, then it is not possible for the current to be flowing from B to A.

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012



A 2.0-μF capacitor is plugged into a 110 V-rms 60-Hz voltage source, with an ammeter in series. What is the rms value of the

current into or out of the capacitor?


At a distance of 10.0 km from a radio transmitter, the amplitude of the radiated electric field of the radio transmissions is

measured to be 0.20 volts/meter. Assuming that the radio transmitter is broadcasting with equal intensity in all directions, what is

the total power emitted by the radio station?

0.220 mA (rms)

26.4 mA (rms)

82.9 mA (rms)

2.10 mA (rms)

13.2 mA (rms)

16.7 kW

133 kW

66.7 kW

3.34 W

222 μW

445 μW

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012



An electromagnetic wave is transporting energy in the negative y direction. At one location and one instant the radiated magneticfield is in the positive x direction. The direction of the radiated electric field at that location and at that instant is


A resistor with R = 2.0 kΩ is placed in series with an inductor, a battery, and an open switch. What is the inductance of this circuitif, after the switch is closed, the current increases to 25% of its final value in 30.0 μs?

−y

+y

+x

+z

−z

−x

52 mH

43 mH

17 mH

166 mH

209 mH

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012



The y-component of the radiated magnetic field of a plane electromagnetic wave moving in the z-direction is given by

By(t) = (1.20 μT)sin .

The x-component of the magnetic field is always zero. What is the speed of this electromagnetic wave?

(2π rad) − z290 m

t0.97 μs

22400 m/s

4280 m/s

2.50e+08 m/s

3.00e+08 m/s

4.77e+07 m/s

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012



Two identical silver spheres are located in outer space at different distances from our sun. Sphere 1 is located at a distance R fromthe sun, and sphere 2 is located at a distance 3R from the sun. What is the ratio of the pressure of solar radiation on sphere 2 tothat on sphere 1;; i.e. what is the ratio

(radiation pressure on sphere 2) : (radiation pressure on sphere 1)?

1 : 3

1 : 1

1 : 9

9 : 1

3 : 1

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012


10.1/1 points | Previous Answers

The primary winding of an electric train transformer has 400 turns and the secondary has 100 turns. If the RMS input voltage is120 V, what is the RMS output voltage?


An inductor, a capacitor, and a 64.0-Ω resistor are connected in series with an AC generator;; the generator produces an RMSvoltage of 90 V. If the impedance of the circuit is 105 Ω, what is the average power output of the generator?

480 V (rms)

7.50 V (rms)

60.0 V (rms)

240 V (rms)

30.0 V (rms)

47.0 W

127 W

208 W

18.2 W

77.1 W

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012



A time-dependent EMF of (8.00 V)sin((1800 rad/s)t) is applied to a series RLC circuit, with R = 200 Ω, L = 0.100 H, andC = 1.00 μF. What are the resulting impedance and phase constant?


A capacitor with C = 36.0 mF is placed in series with a 12.0-V battery and an inductor having L = 200 mH. The resistance in thecircuit is small enough to ignore. What is the frequency of electromagnetic oscillations in the circuit?


576 Ω, −69.7 degrees


3662 Ω, −86.9 degrees


3468 Ω, −86.7 degrees

11.8 Hz

1.88 Hz

0.982 Hz

22.5 Hz

13.9 Hz

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012


The switch in the circuit shown below is a two-way switch;; to prevent sparking, the switch is also a "make-before-break" switch,

meaning that, in moving from a to b, the switch makes contact at b an instant before losing contact at a. When the switch is inposition a, the inductor L is in series with the battery and resistor Ra. When the switch is in position b, the inductor L is in series

with resistor Rb.

Assume that Ra = 10.0 Ω, L = 2.5 H, Rb = 20.0 Ω, and VB = 100 V, and also assume that the switch is first moved to position b.

After a long time, the switch is then moved to position a. Immediately after moving the switch to position a, what will be theabsolute value of the rate of change of current in resistor Ra?

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012



A resistor R, an ideal inductor L, and a capacitor C are connected in series to an AC generator having an EMF given by

(t) = maxsin(ωt).

If the current in this circuit is written as

I(t) = Imaxsin(ωt − φ),

then conservation of power for the circuit, averaged over one cycle, may be written as

rmsIrmscos(φ) = (Irms)2R.

Evaluate the correctness of the following three statements relating to this conservation of power equation.

(a) For this circuit, power is NOT conserved at every instant of time;; power is conserved only if one averages over a full cycle.

10.0 A/s

15.0 A/s

120.0 A/s

3.33 A/s

40.0 A/s

80.0 A/s

12/13/12 PHY131-‐‑Test #4-‐‑Fall2012


(b) For this circuit, power is conserved only at resonance, when φ = 0, and thus cos(φ) = 1.

(c) For this circuit, the average power output of the generator is always less than rmsIrms, except when the circuit is atresonance.

True

False

True

False

True

False

12/13/12 11:34 PMPHY131-Test #4-Fall2012

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A 100-kW radio station emits EM waves in all directions from an antenna on top of a mountain. What isthe intensity of this EM radiation at a distance of 20.0 km from the antenna?


A 10.0-Ω resistor and a 300-µF capacitor are connected in series with a 60.0-Hz AC generator having apeak voltage of 110 V. What is the impedance of this circuit?

PHY131-Test #4-Fall2012 (Test)Mason MechlerPHY-131 Fall 2012, Fall 2012Instructor: Ricardo Alarcon

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39.8 µW

0.796 W

79.6 µW

19.9 µW

2.98 nW

1.16 Ω

4.67 Ω

18.8 Ω

13.3 Ω

310 Ω

12/13/12 11:34 PMPHY131-Test #4-Fall2012


3. 0.5/1 points | Previous Answers

For the circuit shown below, in the branch of the circuit containing the capacitor and the ammeter, theresistance is small enough to ignore.

(a) Assume that the switch S is suddenly closed after having been open for a long time. Immediately afterclosing the switch, what will be the direction of the current in the ammeter?

(b) After being closed for a long time, the switch S is suddenly opened. Immediately after opening theswitch, what will be the direction of the current in the ammeter?

From a to b.

From b to a.

Since there is not a complete circuit in that branch, the current in the ammeter will be zero.

From a to b.

Since there is not a complete circuit in that branch, the current in the ammeter will be zero;besides, the battery is no longer connected to the circuit.

From b to a.

12/13/12 11:34 PMPHY131-Test #4-Fall2012



The y-component of the radiated magnetic field of a plane electromagnetic wave moving in the z-directionis given by

By(t) = (3.20 µT)sin .

The x-component of the magnetic field is always zero. For this electromagnetic wave, what is theamplitude of the radiated electric field?


Assume that radiant energy from the sun arrives at your location with an intensity of 930 W/m2. In thisEM radiation, what are the maximum values of the radiated electric and magnetic fields?

(2π rad) − z240 m

t0.80 µs

4.00 V/m

960 V/m

1.07 V/m

768 V/m

679 V/m

418 V/m, 1.39 µT

592 V/m, 1.97 µT

10.3 MV/m, 34.2 mT

7.25 MV/m, 24.2 mT

837 V/m, 2.79 µT

14.5 MV/m, 48.3 mT

12/13/12 11:34 PMPHY131-Test #4-Fall2012



A 1.00-kΩ resistor, a 0.200-H inductor, and a 1.00-µF capacitor are connected in series with an ACgenerator; the EMF of the generator is given by (150 V)sin((377 rad/s)t). What is the amplitude of theresulting alternating current?


At what frequency will a 12-µF capacitor have a reactance of 400 Ω?

38.4 mA

54.3 mA

8.99 mA

27.1 mA

150 mA

33.2 Hz

208 Hz

4.80 mHz

5.31 Hz

5.31 MHz

12/13/12 11:34 PMPHY131-Test #4-Fall2012



A resistor with R = 4.0 kΩ is placed in series with a 240-V battery, an open switch, and an inductorhaving L = 36.0 mH. After the switch has been closed, how much time is required for the current in thecircuit to reach 75% of its maximum value? Give your answer as a fraction or multiple of the timeconstant for the circuit.

0.721 time constants


3.48 time constants

1.39 time constants

1.33 time constants


12/13/12 11:34 PMPHY131-Test #4-Fall2012



The switch in the circuit shown below is a two-way switch; to prevent sparking, the switch is also a"make-before-break" switch, meaning that, in moving from a to b, the switch makes contact at b aninstant before losing contact at a. When the switch is in position a, the inductor L is in series with thebattery and resistor Ra. When the switch is in position b, the inductor L is in series with resistor Rb.

Assume that Ra = 8.0 Ω, L = 6.0 H, Rb = 20.0 Ω, and VB = 100 V, and also assume that the switch is

first moved to position a. After a long time, the switch is then moved to position b. Immediately aftermoving the switch to position b, what will be the absolute value of the induced EMF in the inductor L?

28.6 V

40.0 V

250 V

100 V

71.4 V

140 V

12/13/12 11:34 PMPHY131-Test #4-Fall2012



Two identical silver spheres are located in outer space at different distances from our sun. Sphere 1 is

located at a distance R from the sun, and sphere 2 is located at a distance 6R from the sun. For sphere1, let the symbol T1 represent the ratio of the gravitational force exerted on sphere 1 by the sun to the

pressure of solar radiation on sphere 1, i.e.

T1 = .

Let T2 represent the same ratio for sphere 2, i.e.

T2 = .

What is the ratio of the value of T2 to the value of T1; i.e. what is

T2 : T1?

FG on 1 by the sunPrad on 1

FG on 2 by the sunPrad on 2

6 : 1

36 : 1

1 : 6

1 : 1

1 : 36

12/13/12 11:34 PMPHY131-Test #4-Fall2012



A resistor, an ideal inductor, and a capacitor are connected in series to a sinusoidal source of EMF havingperiod T. Evaluate the correctness of the following four statements.

(a) The current in the inductor reaches its maximum value T/4 seconds before the current in the resistorreaches its maximum value.

(b) The current in the inductor reaches its maximum value T/4 seconds after the current in the resistorreaches its maximum value.

(c) The voltage across the inductor reaches its maximum value T/4 seconds before the voltage across theresistor reaches its maximum value.

(d) The voltage across the inductor reaches its maximum value T/4 seconds after the voltage across theresistor reaches its maximum value.

True

False

True

False

True

False

True

False

12/13/12 11:34 PMPHY131-Test #4-Fall2012



The primary winding of an step-up transformer has 100 turns and the secondary has 1200 turns. If theRMS input voltage is 110 V, what is the RMS output voltage?

15800 V (rms)

9.17 V (rms)

381 V (rms)

31.8 V (rms)

1320 V (rms)

12/13/12 11:34 PMPHY131-Test #4-Fall2012



Before the switch is closed in the figure, the voltage across the capacitor is 200 V. At some instant afterthe switch is closed, the instantaneous current is 0.40 A. If L = 0.20 H and C = 4.0 µF, then what is theenergy in the capacitor at this instant?

16 mJ

64 mJ

36 mJ

80 mJ

96 mJ

12/13/12 11:34 PMPHY131-Test #4-Fall2012



A capacitor with C = 36.0 mF is placed in series with a 12.0-V battery and an inductor having L = 250mH. The resistance in the circuit is small enough to ignore. What is the frequency of electromagneticoscillations in the circuit?


A 10.0-Ω resistor, a 0.100-H inductor, and a 10.0-µF capacitor are connected in series with an ACgenerator; the generator produces an RMS voltage of 100 V. If the generator is operated at the resonancefrequency of the circuit, what will be the resulting average power dissipation?

1.68 Hz

20.1 Hz

13.7 Hz

10.5 Hz

0.878 Hz

49.9 W

500 W

1000 W

zero, since the circuit will be at resonance

2000 W

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PHY131-Test #4-Fall2012 (Test)

Kevin Winarta

PHY-131 Fall 2012, Fall 2012Instructor: Ricardo Alarcon

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For the circuit shown below, in the branch of the circuit containing the capacitor and the ammeter, the

resistance is small enough to ignore.

(a) Assume that the switch S is suddenly closed after having been open for a long time. Immediately

after closing the switch, what will be the direction of the current in the ammeter?

(b) After being closed for a long time, the switch S is suddenly opened. Immediately after opening the

switch, what will be the direction of the current in the ammeter?

From b to a.

Since there is not a complete circuit in that branch, the current in the ammeter will be zero.

From a to b.

From a to b.

Since there is not a complete circuit in that branch, the current in the ammeter will be zero;

besides, the battery is no longer connected to the circuit.

From b to a.


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A 2.0-μF capacitor is plugged into a 110 V-rms 60-Hz voltage source, with an ammeter in series. What is

the rms value of the current into or out of the capacitor?


A 100-kW radio station emits EM waves in all directions from an antenna on top of a mountain. What is

the intensity of this EM radiation at a distance of 10.0 km from the antenna?

82.9 mA (rms)

2.10 mA (rms)

13.2 mA (rms)

26.4 mA (rms)

0.220 mA (rms)

159 μW

1.59 W

79.6 μW

23.9 nW

318 μW




A 10.0-Ω resistor and a 500-μF capacitor are connected in series with a 60.0-Hz AC generator having a

peak voltage of 110 V. What is the impedance of this circuit?


The primary winding of an electric train transformer has 400 turns and the secondary has 40 turns. If

the RMS input voltage is 120 V, what is the RMS output voltage?

11.3 Ω

15.3 Ω

510 Ω

4.69 Ω

8.48 Ω

12.0 V (rms)

1200 V (rms)

37.9 V (rms)

1.20 V (rms)

379 V (rms)




A resistor, an ideal inductor, and a capacitor are connected in series to a sinusoidal source of EMF

having period T. Evaluate the correctness of the following four statements.

(a) The current in the inductor reaches its maximum value T/4 seconds before the current in the resistor

reaches its maximum value.

(b) The current in the inductor reaches its maximum value T/4 seconds after the current in the resistor

reaches its maximum value.

(c) The voltage across the inductor reaches its maximum value T/4 seconds before the voltage across

the resistor reaches its maximum value.

(d) The voltage across the inductor reaches its maximum value T/4 seconds after the voltage across the

resistor reaches its maximum value.

True

False

True

False

True

False

True

False




A circuit contains two inductors of 10.0 mH inductance in parallel placed in series with an inductor of 8.0

mH inductance. After one of the 10.0 mH inductors burns out, the repairman wants to replace all three

inductors with one inductor of equivalent inductance. Assuming inductors combine in series and parallel

the same way resistors do, what inductance should he use?


The y-component of the radiated magnetic field of a plane electromagnetic wave moving in the z-

direction is given by

By(t) = (1.20 μT)sin .

The x-component of the magnetic field is always zero. For this electromagnetic wave, what is the

amplitude of the radiated electric field?

3.1 mH

28.0 mH

8.2 mH

13.0 mH

5.7 mH

(2π rad) − z

240 m

t

0.80 μs

0.400 V/m

1.50 V/m

360 V/m

288 V/m

255 V/m



located at a distance R from the sun, and sphere 2 is located at a distance 3R from the sun. What is

the ratio of the pressure of solar radiation on sphere 2 to that on sphere 1; i.e. what is the ratio


1 : 9

9 : 1

1 : 1

3 : 1

1 : 3

12/13/12



The inductor shown in the figure below is a part of a complete circuit; the rest of the circuit is not

shown. For all parts of this question, you are given that the electric potential at location A is higher than

the electric potential at location B.

(a) Consider the possibility that the current through this inductor is from A to B. Recall that the potential

is higher at location A. Which of the following statements is most accurate?

(b) Consider the possibility that the current through this inductor is from B to A. Recall that the potential is higher atlocation A. Which of the following statements is most accurate?

Viewing Saved Work Revert to Last Response

The amount of current must be increasing. The amount of current must be decreasing.

The amount of current may either be steady or increasing, but not decreasing. The amount of

current may either be steady or decreasing, but not increasing. The amount of current may either

be steady, increasing, or decreasing. If the potential is higher at A, then it is not possible for the

current to be flowing from A to B.

The amount of current must be increasing. The amount of current must be decreasing. The amount

of current may either be steady or increasing, but not decreasing. The amount of current may either be steady or

decreasing, but not increasing. The amount of current may either be steady, increasing, or decreasing. If thepotential is higher at A, then it is not possible for the current to be flowing from B to A.

12/13/12



An inductor, a capacitor, and a 64.0-Ω resistor are connected in series with an AC generator; the

generator produces an RMS voltage of 90 V. If the impedance of the circuit is 135 Ω, what is the

average power output of the generator?


Assume that radiant energy from the sun arrives at your location with an intensity of 970 W/m2. In this

EM radiation, what are the maximum values of the radiated electric and magnetic fields?

28.4 W

13.1 W

60.0 W

267 W

127 W

427 V/m, 1.42 μT

855 V/m, 2.85 μT

604 V/m, 2.01 μT

7.40 MV/m, 24.7 mT

10.5 MV/m, 34.9 mT

14.8 MV/m, 49.4 mT




A time-dependent EMF of (8.00 V)sin((2000 rad/s)t) is applied to a series RLC circuit, with R = 200 Ω,

L = 0.100 H, and C = 1.00 μF. What are the resulting impedance and phase constant?


A resistor with R = 2.0 kΩ is placed in series with an inductor, a battery, and an open switch. What is

the inductance of this circuit if, after the switch is closed, the current increases to 25% of its final

value in 40.0 μs?




3310 Ω, −86.5 degrees

3116 Ω, −86.3 degrees

222 mH

23 mH

70 mH

58 mH

278 mH




The switch in the circuit shown below is a two-way switch; to prevent sparking, the switch is also a

"make-before-break" switch, meaning that, in moving from a to b, the switch makes contact at b an

instant before losing contact at a. When the switch is in position a, the inductor L is in series with the

battery and resistor Ra. When the switch is in position b, the inductor L is in series with resistor Rb.

Assume that Ra = 12.0 Ω, L = 6.0 H, Rb = 20.0 Ω, and VB = 100 V, and also assume that the switch

is first moved to position a. After a long time, the switch is then moved to position b. Immediately after

moving the switch to position b, what will be the absolute value of the induced EMF in the inductor L?

100 V

160 V

60.0 V

167 V

62.5 V

37.5 V

12/13/12 9:45 PMPHY131-Test #4-Fall2012

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The primary winding of an electric train transformer has 400 turns and the secondary has 40 turns. Ifthe RMS input voltage is 120 V, what is the RMS output voltage?

PHY131-Test #4-Fall2012 (Test)Sean BuizerPHY-131 Fall 2012, Fall 2012Instructor: Ricardo Alarcon

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1200 V (rms)

12.0 V (rms)

37.9 V (rms)

1.20 V (rms)

379 V (rms)

12/13/12 9:45 PMPHY131-Test #4-Fall2012



The switch in the circuit shown below is a two-way switch. With the switch in position a, the capacitor isbeing charged by the battery through resistor R. If the switch is then moved to position b, the chargedcapacitor will be able to discharge through the inductor L; the resistance in the discharging circuit issmall enough to ignore.

Assume that the switch is first moved to position a. After a long time, the switch is then moved toposition b. If C = 36.0 mF, L = 300 mH, R = 50.0 Ω, and VB = 15.0 V, then what is the best description

of the resulting current in the discharging circuit?

An alternating current having a frequency of 60.5 Hz

An exponentially-decaying direct current having a time constant of 1.80 s


An exponentially-decaying direct current having a time constant of 12.0 ms


An exponentially-decaying direct current having a time constant of 6.00 ms

12/13/12 9:45 PMPHY131-Test #4-Fall2012



The switch in the circuit shown below is a two-way switch; to prevent sparking, the switch is also a"make-before-break" switch, meaning that, in moving from a to b, the switch makes contact at b aninstant before losing contact at a. When the switch is in position a, the inductor L is in series with thebattery and resistor Ra. When the switch is in position b, the inductor L is in series with resistor Rb.

Assume that Ra = 8.0 Ω, L = 6.0 H, Rb = 20.0 Ω, and VB = 100 V, and also assume that the switch is

first moved to position a. After a long time, the switch is then moved to position b. Immediately aftermoving the switch to position b, what will be the absolute value of the induced EMF in the inductor L?

71.4 V

28.6 V

140 V

250 V

40.0 V

100 V

12/13/12 9:45 PMPHY131-Test #4-Fall2012



The y-component of the radiated magnetic field of a plane electromagnetic wave moving in the z-direction is given by

By(t) = (1.20 µT)sin .

The x-component of the magnetic field is always zero. What is the wavelength of this electromagneticwave?


A circuit contains two inductors of 20.0 mH inductance in parallel placed in series with an inductor of 8.0mH inductance. After one of the 20.0 mH inductors burns out, the repairman wants to replace all threeinductors with one inductor of equivalent inductance. Assuming inductors combine in series and parallelthe same way resistors do, what inductance should he use?

(2π rad) − z290 m

t0.97 µs

4.14 mm

242 m

46.2 m

290 m

21.7 mm

18.0 mH

48.0 mH

4.4 mH

6.7 mH

8.1 mH

12/13/12 9:45 PMPHY131-Test #4-Fall2012



A 10.0-Ω resistor and a 45.0-mH inductor are connected in series with a 60.0-Hz AC generator having apeak voltage of 110 V. What is the impedance of this circuit?

2700 Ω

19.7 Ω

12.7 Ω

55.0 Ω

27.0 Ω

12/13/12 9:45 PMPHY131-Test #4-Fall2012



For the circuit shown below, in the branch of the circuit containing the capacitor and the ammeter, theresistance is small enough to ignore.

Assume that RA = 2.0 Ω, C = 2.0 µH, RB = 5.0 Ω, and VB = 12.0 V. Assume that the switch S is

suddenly closed after having been open for a long time. A long time after closing the switch, what will bethe voltage across the capacitor?

zero

12.0 V

30.0 V

3.43 V

42.0 V

8.57 V

12/13/12 9:45 PMPHY131-Test #4-Fall2012



A resistor, an ideal inductor, and a capacitor are connected in series to a sinusoidal source of EMF havingperiod T. Use the pulldown boxes to fill in the blanks in the two statements below. Statement (a) will askyou to compare the timing of the current in the inductor with the timing of the current in the resistor.Statement (b) will ask you to compare the timing of the voltage across each of the same two circuitelements.

(a) The current in the inductor reaches its maximum value at the same time as the current in theresistor reaches its maximum value.

(b) The voltage across the inductor reaches its maximum value T/4 seconds before the voltageacross the resistor reaches its maximum value.


Determine the amount of energy carried in 11.0 meters of a 3.50-mW He-Ne laser beam if the cross-

sectional area of the beam is 5.00 × 10-6 m2.

1.28e-10 joules

1.93e-07 joules

6.42e-16 joules

1.59e-09 joules

2.57e-05 joules

7.70e-09 joules

12/13/12 9:45 PMPHY131-Test #4-Fall2012




located at a distance R from the sun, and sphere 2 is located at a distance 2R from the sun. What is theratio of the pressure of solar radiation on sphere 2 to that on sphere 1; i.e. what is the ratio



A 4.00-kΩ resistor and a 2.00-µF capacitor are connected in series with an AC generator; the EMF of thegenerator is given by (170 V)cos((300 rad/s)t). What is the average power dissipation in this circuit?

1 : 2

2 : 1

4 : 1

1 : 1

1 : 4

7.23 W

1.54 W

3.61 W

3.08 W

3.33 W

12/13/12 9:45 PMPHY131-Test #4-Fall2012



A 100-kW radio station emits EM waves in all directions from an antenna on top of a mountain. What isthe intensity of this EM radiation at a distance of 10.0 km from the antenna?


A resistor with R = 2.0 kΩ is placed in series with an inductor, a battery, and an open switch. What isthe inductance of this circuit if, after the switch is closed, the current increases to 25% of its final valuein 50.0 µs?

1.59 W

23.9 nW

318 µW

159 µW

79.6 µW

87 mH

277 mH

72 mH

348 mH

29 mH

12/13/12 9:45 PMPHY131-Test #4-Fall2012



As shown in the circuit diagram below, four AC voltmeters are connected to a series circuit whichcontains a resistor, an ideal inductor, a capacitor, and an AC generator. The voltmeters read RMSvalues. When the generator is operating at an angular frequency of 650 rad/s, the RMS current in the

circuit is 0.125 A. For these conditions, determine the reading on voltmeter V4.

81.3 V

125 V

274 V

111 V

192 V

12/13/12 9:45 PMPHY131-Test #4-Fall2012



A 10.0-mH inductor and a 100-Ω resistor are connected in series with an AC generator. The resultingcurrent in the circuit is given by

I(t) = (3.0 A)sin((4000 rad/s)t).

What is the average power loss in this circuit?

900 W

485 W

969 W

450 W

630 W

Current Score : – / 24 Due : Tuesday, December 3 2013 11:59 PM MST

1. –/1 points

What is the inductance of a series RL circuit in which R = 1.0 KΩ if the current increases to one-third ofits final value in 30 µs?

99 mH

49 mH

62 mH

74 mH

29 mH

PHY-131-REVIEW-TEST4(not for grade) (Practice Test)Mahmoud MirzaPHY-131 University Physics II, Fall 2013Instructor: Ricardo Alarcon

WebAssign


Important! Before you view the answer key, decide whether or not you plan to request an extension. Your Instructor maynot grant you an extension if you have viewed the answer key. Automatic extensions are not granted if you have viewed theanswer key.

Request Extension

2. –/1 points

For the circuit shown, what is the rate of change of the current in the inductor when the current in thebattery is 0.50 A?

600 A/s

400 A/s

800 A/s

200 A/s

500 A/s

3. –/1 points

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The angularfrequency of the electromagnetic oscillations in the circuit is

36.0 × 10-4 rad/s

6.00 × 10-2 rad/s

2.78 rad/s

16.7 rad/s

277 rad/s

4. –/1 points

The figure shows an LR circuit with a switch and a 240-volt battery.

At the instant the switch is closed the current in the circuit and the potential difference between points aand b, Vab, are

0 A, 0 V

0 A, −240 V

0.024 A, 0 V

0 A, +240 V

0.024 A, +240 V

5. –/1 points

A series LC circuit contains a 100 mH inductor, a 36.0 mF capacitor and a 12 V battery. The period of theelectromagnetic oscillations in the circuit is

0.0227 s.

2.26 s.

105 s.

0.377 s.

1750 s.

6. –/1 points

A circuit contains two inductors of 6.0 mH inductance in series placed in parallel with an inductor of 8.0mH inductance. After one of the 6.0 mH inductors burns out, the repairman wants to replace all threeinductors with one inductor of equivalent inductance. Assuming inductors combine in series and parallelthe same way resistors do, what inductance should he use?

3.0 mH

3.4 mH

11 mH

4.8 mH

20 mH

7. –/1 points

An electric heater draws an average power of 1100 Watts when plugged into a 110 V-rms outlet.Calculate the resistance of the heater and the rms current.

110 Ω, 10 A (rms)

10 Ω, 11 A (rms)

10 Ω, 110 A (rms)

11 Ω, 10 A (rms)

0.09 Ω, 11 A (rms)

8. –/1 points

A 2.0-µF capacitor in series with a 2.0-kΩ resistor is connected to a 60-Hz ac source. Calculate theimpedance of the circuit.

1500 ohms

1800 ohms

2100 ohms

2400 ohms

8600 ohms

9. –/1 points

A 0.500-H inductor is connected into a 110 V-rms 60.0-Hz voltage source, with an ammeter in series.What is the rms value of the current through the inductor?

0.189 A (rms)

0.292 A (rms)

1.19 A (rms)

0.584 A (rms)

0.093 A (rms)

10.–/1 points

Find the resonant frequency for a series RLC circuit where R = 10 Ω, C = 5.00 µF, and L = 2.00 mH.998 Hz

2.45 kHz

11.3 kHz

1.59 kHz

2.53 kHz

11.–/1 points

Determine the impedance for the circuit.

600 Ω

1200 Ω

2300 Ω

1800 Ω

1100 Ω

12.–/1 points

Determine the resonant frequency of the circuit.

32 Hz

5 Hz

500 Hz

159 Hz

79.5 Hz

13.–/1 points

Determine the rms voltage drop across the capacitor in the circuit.

55 V

77 V

154 V

110 V

198 V

14.–/1 points

A current I = 3 sin (400 t) amperes flows in a series RL circuit in which L = 1 mH and R = 100Ω. What isthe average power loss?

225 W

980 W

1.12 kW

450 W

900 W

15.–/1 points

A transformer is to be designed to increase the 30 kV-rms output of a generator to the transmission-linevoltage of 345 kV-rms. If the primary winding has 80 turns, how many turns must the secondary have?

12

70

9200

920

120

16.–/1 points

All three circuits below have R = 100 Ω, C = 1.0 mF and emf ε = (5.0 V) sin (377 t). The inductors in(B) and (C) are placed sufficiently far apart so that they do not alter one another's inductance. Suchinductors add combine like resistors. Which statement regarding the angular resonance frequencies ωA,

ωB and ωC is correct?

ωC > ωA = ωB

ωC < ωA = ωB

ωB < ωA = ωC

ωA = ωB = ωC

ωB > ωA = ωC

17.–/1 points

A 60.0-Hz ac generator with a peak voltage of 110 V drives a series RL circuit with R = 10.0 Ω and L =10.0 mH. The peak current in the circuit is

0.963 A

11.0 A

11.9 A

10.3 A

29.2 A

18.–/1 points

If the maximum E-component of an electromagnetic wave is 600 V/m, what is the maximum B-component?

1.4 T

1.8 × 10−5 T

1.0 × 10−3 T

2.0 × 10−6 T

1.6 × 10−10 T

19.–/1 points

What is the average value of the magnitude of the Poynting vector at 1 meter from a 100-watt lightbulbradiating in all directions?

1 W/m2

4 W/m2

2 W/m2

8 W/m2

12 W/m2

20.–/1 points

The magnetic field of a plane-polarized electromagnetic wave moving in the z-direction is given by

in SI units. What is the frequency of the wave?

500 MHz

250 kHz

10 mHz

1.25 MHz

300 MHz

21.–/1 points

The magnetic field of a plane-polarized electromagnetic wave moving in the z-direction is given by

in SI units. Find the average power per square meter

carried by the EM wave.720 W

500 W

2 × 107 W

172 W

86 W

B = 1.2 x 10−6 sin 2π − z240

t x 107

8

B = 1.2 x 10−6 sin 2π − z240

t x 107

8

22.–/1 points

In an electromagnetic wave, 1) how are the electric and magnetic field directions related and 2) how is

the direction of travel determined from their directions? ( is the velocity of the light wave.)

23.–/1 points

When E and B are the amplitudes of the electric and magnetic fields in an electromagnetic wave invacuum, the total average energy density in the wave is

c

|| and = E Bc

c x

x

B E

B E

|| and = E Bc

c x

x

E B

E B

| and = E Bc

c x

x

E B

E B

| and = E Bc

c x

x

B E

B E

ε0E214

ε0E2

B2

μ0

ε0E212

EBμ0

24.–/1 points

A plane parallel plate capacitor has plates of 10 cm2 area that are 1.0 mm apart. At an instant whencharge is being accumulated on the plates at a rate of 12 nC/s, the displacement current between theplates is

1.06 × 10−16 A

8.85 × 10−9 A

1.00 A

1.2 × 10−8 A

1.36 A

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WebAssign Girish Pathangey PHY131 Test #4 Fall2012 (Test ...docshare04.docshare.tips/files/20690/206900359.pdf · Girish Pathangey PHY 131 Fall 2012, Fall 2012 Instructor: Ricardo