Question 1

The electrical analog of a spring constant k is:

Accepted Answer

A)  L 
B)  1/L 
C)  C 
D)  1/C 
E)  R 
A)  L 
B)  1/L 
C)  C 
D)  1/C 
E)  R D

Question 2

A sinusoidal voltage V(t) has an rms value of 100 V. Its maximum value is:

Accepted Answer

A)  100 V 
B)  707 V 
C)  70.7 V 
D)  141 V 
E)  200 V 
A)  100 V 
B)  707 V 
C)  70.7 V 
D)  141 V 
E)  200 V D

Question 3

In a purely resistive circuit the current:

Accepted Answer

A)  leads the voltage by 1/4 cycle 
B)  leads the voltage by 1/2 cycle 
C)  lags the voltage by 1/4 cycle 
D)  lags the voltage by 1/2 cycle 
E)  is in phase with the voltage 
A)  leads the voltage by 1/4 cycle 
B)  leads the voltage by 1/2 cycle 
C)  lags the voltage by 1/4 cycle 
D)  lags the voltage by 1/2 cycle 
E)  is in phase with the voltage E

Question 4

The impedance of an RLC series circuit is definitely increased if:

Accepted Answer

A)  C decreases 
B)  L increases 
C)  L decreases 
D)  R increases 
E)  R decreases 
A)  C decreases 
B)  L increases 
C)  L decreases 
D)  R increases 
E)  R decreases

Question 5

The core of a transformer is made in a laminated form to:

Accepted Answer

A)  facilitate easy assembly 
B)  reduce i2R losses in the coils 
C)  increase the magnetic flux 
D)  save weight 
E)  prevent eddy currents 
A)  facilitate easy assembly 
B)  reduce i2R losses in the coils 
C)  increase the magnetic flux 
D)  save weight 
E)  prevent eddy currents

Question 6

The rms value of an ac current is:

Accepted Answer

A)  its peak value 
B)  its average value 
C)  that steady current that produces the same rate of heating in a resistor 
D)  that steady current that will charge a battery at the same rate 
E)  zero 
A)  its peak value 
B)  its average value 
C)  that steady current that produces the same rate of heating in a resistor 
D)  that steady current that will charge a battery at the same rate 
E)  zero

Question 7

The units of the power factor are:

Accepted Answer

A)  ohm 
B)  watt 
C)  radian 
D)  ohm1/2 
E)  none of these 
A)  ohm 
B)  watt 
C)  radian 
D)  ohm1/2 
E)  none of these

Question 8

In an oscillating LC circuit, the total stored energy is U and the maximum charge on the capacitor is Q.When the charge on the capacitor is Q/2, the energy stored in the inductor is:

Accepted Answer

A)  U/2 
B)  U/4 
C)  (4/3)U 
D)  3U/2 
E)  3U/4 
A)  U/2 
B)  U/4 
C)  (4/3)U 
D)  3U/2 
E)  3U/4

Question 9

A generator supplies 100 V to the primary coil of a transformer. The primary has 50 turns and the secondary has 500 turns.The secondary voltage is:

Accepted Answer

A)  1000 V 
B)  500 V 
C)  250 V 
D)  100 V 
E)  10 V 
A)  1000 V 
B)  500 V 
C)  250 V 
D)  100 V 
E)  10 V

Question 10

In a purely inductive circuit, the current lags the voltage by:

Accepted Answer

A)  0 
B)  one-fourth of a cycle 
C)  one-half of a cycle 
D)  three-fourths of a cycle 
E)  one cycle 
A)  0 
B)  one-fourth of a cycle 
C)  one-half of a cycle 
D)  three-fourths of a cycle 
E)  one cycle

Question 11

A step-down transformer is used to:

Accepted Answer

A)  increase the power 
B)  decrease the power 
C)  increase the voltage 
D)  decrease the voltage 
E)  change ac to dc 
A)  increase the power 
B)  decrease the power 
C)  increase the voltage 
D)  decrease the voltage 
E)  change ac to dc

Question 12

When the frequency of the oscillator in a series RLC circuit is doubled:

Accepted Answer

A)  the capacitive reactance is doubled 
B)  the capacitive reactance is halved 
C)  the impedance is doubled 
D)  the current amplitude is doubled 
E)  the current amplitude is halved 
A)  the capacitive reactance is doubled 
B)  the capacitive reactance is halved 
C)  the impedance is doubled 
D)  the current amplitude is doubled 
E)  the current amplitude is halved

Question 13

A 45-mH inductor is connected to an ac source of emf with a frequency of 400 Hz and a maximum emf of 20 V. The maximum current is:

Accepted Answer

A)  0 
B)  0.18 A 
C)  1.1 A 
D)  360 A 
E)  2300 A 
A)  0 
B)  0.18 A 
C)  1.1 A 
D)  360 A 
E)  2300 A

Question 14

The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might due to:

Accepted Answer

A)  a large inductance 
B)  a large capacitance 
C)  a small capacitance 
D)  a large resistance 
E)  a small resistance 
A)  a large inductance 
B)  a large capacitance 
C)  a small capacitance 
D)  a large resistance 
E)  a small resistance

Question 15

In an ideal 1:8 step-down transformer, the primary power is 10 kW and the secondary current is 25 A. The primary voltage is:

Accepted Answer

A)  25,600 V 
B)  3200 V 
C)  400 V 
D)  50 V 
E)  6.25 V 
A)  25,600 V 
B)  3200 V 
C)  400 V 
D)  50 V 
E)  6.25 V

Question 16

A 150-g block on the end of a spring with a spring constant of 35 N/m is pulled aside 25 cm and released from rest. In the electrical analog the initial charge on the capacitor is:

Accepted Answer

A)  0.15 C 
B)  6.67 C 
C)  0.025 C 
D)  40 C 
E)  35 C 
A)  0.15 C 
B)  6.67 C 
C)  0.025 C 
D)  40 C 
E)  35 C

Question 17

An RL series circuit is connected to an ac generator with a maximum emf of 20 V. If the maximum potential difference across the resistor is 16 V, then the maximum potential difference across the inductor is:

Accepted Answer

A)  2 V 
B)  4 V 
C)  12 V 
D)  25.6 V 
E)  36 V 
A)  2 V 
B)  4 V 
C)  12 V 
D)  25.6 V 
E)  36 V

Exam 15: Electromagnetic Oscillations and Alternating Current

The electrical analog of a spring constant k is:

A sinusoidal voltage V(t) has an rms value of 100 V. Its maximum value is:

In a purely resistive circuit the current:

The impedance of an RLC series circuit is definitely increased if:

The core of a transformer is made in a laminated form to:

The rms value of an ac current is:

The units of the power factor are:

In an oscillating LC circuit, the total stored energy is U and the maximum charge on the capacitor is Q.When the charge on the capacitor is Q/2, the energy stored in the inductor is:

A generator supplies 100 V to the primary coil of a transformer. The primary has 50 turns and the secondary has 500 turns.The secondary voltage is:

In a purely inductive circuit, the current lags the voltage by:

A step-down transformer is used to:

When the frequency of the oscillator in a series RLC circuit is doubled:

A 45-mH inductor is connected to an ac source of emf with a frequency of 400 Hz and a maximum emf of 20 V. The maximum current is:

The rapid exponential decay in just a few cycles of the charge on the plates of capacitor in an RLC circuit might due to:

In an ideal 1:8 step-down transformer, the primary power is 10 kW and the secondary current is 25 A. The primary voltage is:

A 150-g block on the end of a spring with a spring constant of 35 N/m is pulled aside 25 cm and released from rest. In the electrical analog the initial charge on the capacitor is:

An RL series circuit is connected to an ac generator with a maximum emf of 20 V. If the maximum potential difference across the resistor is 16 V, then the maximum potential difference across the inductor is:

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