553 + Mcqs in Electrical Engineering Page 10 McqOptions

451.	A practical current source has a finite internal resistance.
A.	True
B.	False
Answer» B. False

Discussion

452.	Some circuits require more than one voltage or current source.
A.	True
B.	False
Answer» B. False

Discussion

453.	Which of the following power factors results in less energy loss in an RL circuit?
A.	1
B.	0.8
C.	0.4
D.	0.2
Answer» E.

Discussion

454.	If the frequency is halved and the resistance is doubled, the impedance of a series RL circuit
A.	doubles
B.	halves
C.	remains constant
D.	cannot be determined without values
Answer» E.

Discussion

455.	When the frequency of the voltage applied to a series RL circuit is increased, the phase angle
A.	decreases
B.	increases
C.	does not change
D.	cannot be determined without values
Answer» C. does not change

Discussion

456.	If a load is purely inductive and the reactive power is 12 VAR, the apparent power is
A.	0 VA
B.	12 VA
C.	6 VA
D.	24 VA
Answer» C. 6 VA

Discussion

457.	Lenz's law defines the polarity of the induced voltage.
A.	True
B.	False
Answer» B. False

Discussion

458.	A magnetic field is made up of flux lines.
A.	True
B.	False
Answer» B. False

Discussion

459.	Hysteresis is the number of lines of force per unit area in a magnetic field.
A.	True
B.	False
Answer» C.

Discussion

460.	If a conductor is moved back and forth at a constant rate in a constant magnetic field, the voltage in the conductor will reverse polarity.
A.	True
B.	False
Answer» B. False

Discussion

461.	Materials with a low retentivity do not retain a magnetic field very well.
A.	True
B.	False
Answer» B. False

Discussion

462.	A certain amplifier has 600 internal resistance looking from its output. In order to provide maximum power to a 4 speaker, what turns ratio must be used in the coupling transformer?
A.	8
B.	0.8
C.	0.08
D.	80
Answer» D. 80

Discussion

463.	A transformer
A.	changes ac to dc
B.	changes dc to ac
C.	steps up or down dc voltages
D.	steps up or down ac voltages
Answer» E.

Discussion

464.	The primary of a transformer is connected to a 6 V battery. The turns ratio is 1:3 and the secondary load, RL, is 100 . The voltage across the load is
A.	0 V
B.	6 V
C.	18 V
D.	2 V
Answer» B. 6 V

Discussion

465.	How many primary volts must be applied to a transformer with a turns ratio of 0.1 to obtain a secondary voltage of 9 V?
A.	9 V
B.	90 V
C.	900 V
D.	0.9 V
Answer» C. 900 V

Discussion

466.	To step 120 V ac up to 900 V ac, the turns ratio must be
A.	75
B.	750
C.	7.5
D.	0.13
Answer» D. 0.13

Discussion

467.	A certain transformer has a turns ratio of 1 and a 0.85 coefficient of coupling. When 2 V ac is applied to the primary, the secondary voltage is
A.	1.7 V
B.	0.85 V
C.	1 V
D.	0 V
Answer» B. 0.85 V

Discussion

468.	The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 load. The turns ratio is 3:1. What is the secondary voltage?
A.	2 V
B.	20 V
C.	180 V
D.	18 V
Answer» C. 180 V

Discussion

469.	In a certain loaded transformer, the secondary voltage is one-fourth the primary voltage. The secondary current is
A.	one-fourth the primary current
B.	four times the primary current
C.	equal to the primary current
D.	one-fourth the primary current and equal to the primary current
Answer» C. equal to the primary current

Discussion

470.	The primary winding of a power transformer should always be
A.	open
B.	shorted
C.	switched
D.	fused
Answer» E.

Discussion

471.	A reflective load is a load as it appears to the source in the primary of a transformer.
A.	True
B.	False
Answer» B. False

Discussion

472.	The primary winding of a transformer has 110 V ac across it. What is the secondary voltage if the turns ratio is 8?
A.	8.8 V
B.	88 V
C.	880 V
D.	8,800 V
Answer» D. 8,800 V

Discussion

473.	To step 110 V ac down to 20 V ac, the turns ratio must be
A.	5.5
B.	18
C.	0.18
D.	0.018
Answer» D. 0.018

Discussion

474.	You cannot convert a voltage source to an equivalent current source, or vice versa.
A.	True
B.	False
Answer» C.

Discussion

475.	A center tap (CT) is a connection at the midpoint of the secondary winding of a transformer.
A.	True
B.	False
Answer» B. False

Discussion

476.	A step-up transformer steps up power.
A.	True
B.	False
Answer» C.

Discussion

477.	A transformer changes ac to dc.
A.	True
B.	False
Answer» C.

Discussion

478.	An autotransformer is one in which the primary and secondary are automatically coupled.
A.	True
B.	False
Answer» C.

Discussion

479.	An ideal current source has zero internal resistance.
A.	True
B.	False
Answer» C.

Discussion

480.	The Thevenin equivalent voltage (VTH) is the short-circuit voltage between two terminals in a circuit.
A.	True
B.	False
Answer» C.

Discussion

481.	Transistors act basically as voltage sources.
A.	True
B.	False
Answer» C.

Discussion

482.	Conversions between delta-type and wye-type circuit arrangements are useful in certain specialized applications.
A.	True
B.	False
Answer» B. False

Discussion

483.	If 25 W of power are applied to the primary of an ideal transformer with a turns ratio of 10, the power delivered to the secondary load is
A.	25 W
B.	0 W
C.	250 W
D.	2.5 W
Answer» B. 0 W

Discussion

484.	A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 . What is the approximate voltage across the load?
A.	7.3 V
B.	73 V
C.	88 V
D.	880 V
Answer» B. 73 V

Discussion

485.	The primary is the winding connected to the source, and the secondary is the winding connected to the load.
A.	True
B.	False
Answer» B. False

Discussion

486.	If the voltage is stepped up, the current is stepped down, and vice versa.
A.	True
B.	False
Answer» B. False

Discussion

487.	A step-down transformer has a turns ratio less than 1.
A.	True
B.	False
Answer» B. False

Discussion

488.	A transformer responds only to dc.
A.	True
B.	False
Answer» C.

Discussion

489.	A transformer consists of two or more cores that are electrically coupled on a common core.
A.	True
B.	False
Answer» C.

Discussion

490.	Norton's equivalent current (IN) is an open-circuit current between two points in a circuit.
A.	True
B.	False
Answer» C.

Discussion

491.	The turns ratio required to match an 80 source to a 320 load is
A.	80
B.	20
C.	4
D.	2
Answer» E.

Discussion

492.	A practical voltage source has a nonzero internal resistance.
A.	True
B.	False
Answer» B. False

Discussion

493.	When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is
A.	12 V
B.	120 V
C.	240 V
D.	2,400 V
Answer» D. 2,400 V

Discussion

494.	A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is
A.	0.2
B.	0.4
C.	5
D.	25
Answer» D. 25

Discussion

495.	What kVA rating is required for a transformer that must handle a maximum load current of 8 A with a secondary voltage of 2 kV?
A.	4 kVA
B.	0.25 kVA
C.	16 kVA
D.	8 kVA
Answer» D. 8 kVA

Discussion

496.	When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
A.	increases
B.	decreases
C.	remains constant
D.	reaches zero
Answer» B. decreases

Discussion

497.	The induced voltage across a coil with 250 turns that is located in a magnetic field that is changing at a rate of 8 Wb/s is
A.	1,000 V
B.	2,000 V
C.	31.25 V
D.	3,125 V
Answer» C. 31.25 V

Discussion

498.	For a given wirewound core, an increase in current through the coil
A.	reverses the flux lines
B.	decreases the flux density
C.	increases the flux density
D.	causes no change in flux density
Answer» D. causes no change in flux density

Discussion

499.	If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density
A.	increases
B.	decreases
C.	remains the same
D.	doubles
Answer» C. remains the same

Discussion

500.	When the current through the coil of an electromagnet reverses, the
A.	direction of the magnetic field reverses
B.	direction of the magnetic field remains unchanged
C.	magnetic field expands
D.	magnetic field collapses
Answer» B. direction of the magnetic field remains unchanged

Discussion

Explore topic-wise MCQs in Engineering.

A practical current source has a finite internal resistance.

Some circuits require more than one voltage or current source.

Which of the following power factors results in less energy loss in an RL circuit?

If the frequency is halved and the resistance is doubled, the impedance of a series RL circuit

When the frequency of the voltage applied to a series RL circuit is increased, the phase angle

If a load is purely inductive and the reactive power is 12 VAR, the apparent power is

Lenz's law defines the polarity of the induced voltage.

A magnetic field is made up of flux lines.

Hysteresis is the number of lines of force per unit area in a magnetic field.

If a conductor is moved back and forth at a constant rate in a constant magnetic field, the voltage in the conductor will reverse polarity.

Materials with a low retentivity do not retain a magnetic field very well.

A certain amplifier has 600 internal resistance looking from its output. In order to provide maximum power to a 4 speaker, what turns ratio must be used in the coupling transformer?

A transformer

The primary of a transformer is connected to a 6 V battery. The turns ratio is 1:3 and the secondary load, RL, is 100 . The voltage across the load is

How many primary volts must be applied to a transformer with a turns ratio of 0.1 to obtain a secondary voltage of 9 V?

To step 120 V ac up to 900 V ac, the turns ratio must be

A certain transformer has a turns ratio of 1 and a 0.85 coefficient of coupling. When 2 V ac is applied to the primary, the secondary voltage is

The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 load. The turns ratio is 3:1. What is the secondary voltage?

In a certain loaded transformer, the secondary voltage is one-fourth the primary voltage. The secondary current is

The primary winding of a power transformer should always be

A reflective load is a load as it appears to the source in the primary of a transformer.

The primary winding of a transformer has 110 V ac across it. What is the secondary voltage if the turns ratio is 8?

To step 110 V ac down to 20 V ac, the turns ratio must be

You cannot convert a voltage source to an equivalent current source, or vice versa.

A center tap (CT) is a connection at the midpoint of the secondary winding of a transformer.

A step-up transformer steps up power.

A transformer changes ac to dc.

An autotransformer is one in which the primary and secondary are automatically coupled.

An ideal current source has zero internal resistance.

The Thevenin equivalent voltage (VTH) is the short-circuit voltage between two terminals in a circuit.

Transistors act basically as voltage sources.

Conversions between delta-type and wye-type circuit arrangements are useful in certain specialized applications.

If 25 W of power are applied to the primary of an ideal transformer with a turns ratio of 10, the power delivered to the secondary load is

A transformer with a 110 V primary has a 15:1 turns ratio. The load resistance, RL, is 120 . What is the approximate voltage across the load?

The primary is the winding connected to the source, and the secondary is the winding connected to the load.

If the voltage is stepped up, the current is stepped down, and vice versa.

A step-down transformer has a turns ratio less than 1.

A transformer responds only to dc.

A transformer consists of two or more cores that are electrically coupled on a common core.

Norton's equivalent current (IN) is an open-circuit current between two points in a circuit.

The turns ratio required to match an 80 source to a 320 load is

A practical voltage source has a nonzero internal resistance.

When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is

A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is

What kVA rating is required for a transformer that must handle a maximum load current of 8 A with a secondary voltage of 2 kV?

When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage

The induced voltage across a coil with 250 turns that is located in a magnetic field that is changing at a rate of 8 Wb/s is

For a given wirewound core, an increase in current through the coil

If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density

When the current through the coil of an electromagnet reverses, the