Question 1

Which of the following statements about inductors are correct? There may be more than one correct choice.

Accepted Answer

A) When it is connected in a circuit,an inductor always resists having current flow through it. 
B) Inductors store energy by building up charge. 
C) When an inductor and a resistor are connected in series with a DC battery,the current in the circuit is reduced to zero in one time constant. 
D) An inductor always resists any change in the current through it. 
E) When an inductor and a resistor are connected in series with a DC battery,the current in the circuit is zero after a very long time. 
A) When it is connected in a circuit,an inductor always resists having current flow through it. 
B) Inductors store energy by building up charge. 
C) When an inductor and a resistor are connected in series with a DC battery,the current in the circuit is reduced to zero in one time constant. 
D) An inductor always resists any change in the current through it. 
E) When an inductor and a resistor are connected in series with a DC battery,the current in the circuit is zero after a very long time.

Question 2

At a certain instant the current flowing through a 5.0-H inductor is 3.0 A.If the energy in the inductor at this instant is increasing at a rate of 3.0 J/s,how fast is the current changing?

Accepted Answer

A) 0.20 A/s 
B) 0.40 A/s 
C) 0.10 A/s 
D) 0.80 A/s 
A) 0.20 A/s 
B) 0.40 A/s 
C) 0.10 A/s 
D) 0.80 A/s

Question 3

A 45-mH ideal inductor is connected in series with a 60-Ω resistor through an ideal 15-V DC power supply and an open switch.If the switch is closed at time t = 0 s,what is the current 7.0 ms later?

Accepted Answer

A) 250 mA 
B) 650 mA 
C) 550 mA 
D) 280 mA 
E) 850 mA 
A) 250 mA 
B) 650 mA 
C) 550 mA 
D) 280 mA 
E) 850 mA

Question 4

A rectangular coil having N turns and measuring 15 cm by 25 cm is rotating in a uniform 1.6-T magnetic field with a frequency of 75 Hz.The rotation axis is perpendicular to the direction of the field.If the coil develops a sinusoidal emf of maximum value 56.9 V,what is the value of N?

Accepted Answer

A) 2 
B) 4 
C) 6 
D) 8 
E) 10 
A) 2 
B) 4 
C) 6 
D) 8 
E) 10

Question 5

Suppose that you wish to construct a simple ac generator having an output of 12 V maximum when rotated at 60 Hz.A uniform magnetic field of 0.050 T is available.If the area of the rotating coil is 100 cm2,how many turns do you need?

Accepted Answer

A) 8 
B) 16 
C) 32 
D) 64 
E) 128 
A) 8 
B) 16 
C) 32 
D) 64 
E) 128

Question 6

A 2.0-m long conducting wire is formed into a square and placed in the horizontal   A uniform magnetic field is oriented   above the horizontal with a strength of   What is the magnetic flux through the square?

Accepted Answer

A) 1.1 T ∙ m2 
B) 1.9 T ∙ m2 
C) 2.3 T ∙ m2 
D) 18 T ∙ m2 
A) 1.1 T ∙ m2 
B) 1.9 T ∙ m2 
C) 2.3 T ∙ m2 
D) 18 T ∙ m2

Exam 30: Electromagnetic Induction

Which of the following statements about inductors are correct? There may be more than one correct choice.

At a certain instant the current flowing through a 5.0-H inductor is 3.0 A.If the energy in the inductor at this instant is increasing at a rate of 3.0 J/s,how fast is the current changing?

A 45-mH ideal inductor is connected in series with a 60-Ω resistor through an ideal 15-V DC power supply and an open switch.If the switch is closed at time t = 0 s,what is the current 7.0 ms later?

A rectangular coil having N turns and measuring 15 cm by 25 cm is rotating in a uniform 1.6-T magnetic field with a frequency of 75 Hz.The rotation axis is perpendicular to the direction of the field.If the coil develops a sinusoidal emf of maximum value 56.9 V,what is the value of N?

Suppose that you wish to construct a simple ac generator having an output of 12 V maximum when rotated at 60 Hz.A uniform magnetic field of 0.050 T is available.If the area of the rotating coil is 100 cm2,how many turns do you need?

A 2.0-m long conducting wire is formed into a square and placed in the horizontal A uniform magnetic field is oriented above the horizontal with a strength of What is the magnetic flux through the square?

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Suppose that you wish to construct a simple ac generator having an output of 12 V maximum when rotated at 60 Hz.A uniform magnetic field of 0.050 T is available.If the area of the rotating coil is 100 cm²,how many turns do you need?