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All Electrical Engineering MCQs

Study 3,658 Electrical Engineering MCQs with correct answers and explanations.

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2691Electrical EngineeringMedium

The efficiency of a properly designed synchronous motor will usually fall in range________?

A75 to 80%

B60 to 70%

C85 to 95%

D99 to 99.5%

Correct answer

C. 85 to 95%

Explanation

The correct answer is 85 to 95%.

2692Electrical EngineeringMedium

A voltmeter should have ________resistance?

ANone of the above

BVery low

CZero

DVery high

Correct answer

D. Very high

Explanation

The correct answer is Very high.

2693Electrical EngineeringMedium

The upper or lower cut off frequency is also called________frequency?

A3 dB

BResonant

CSideband

DNone of the above

Correct answer

A. 3 dB

Explanation

The correct answer is 3 dB.

2694Electrical EngineeringMedium

If two sine waves of the same frequency have a phase difference of JT radians, then________?

Anone of the above

Bboth will reach their maximum values at the same instant

Cwhen one wave reaches its maxi¬mum value, the other will reach its minimum value

Dboth will reach their minimum values at the same instant

Correct answer

C. when one wave reaches its maxi¬mum value, the other will reach its minimum value

Explanation

The correct answer is when one wave reaches its maxi¬mum value, the other will reach its minimum value.

2695Electrical EngineeringMedium

A series resonant band-stop filter consists of a 68 Ω resistor, a 110 mH coil, and a 0.02 µF capacitor. The internal resistance, RW, of the coil is 4 Ω. Input voltage is 200 mV. Output voltage is taken across the coil and capacitor in series. What is the output voltage magnitude at f0?

A11.1 mV

B1.1 mV

C200 mV

D111 mV

Correct answer

A. 11.1 mV

Explanation

The correct answer is 11.1 mV.

2696Electrical EngineeringMedium

The output current in PWM DC – DC converters is equal to________?

ANone of these

BEither A. or B.

CProduct of an average inductor current and a function of duty ratio

DAverage value of the output inductor current

Correct answer

B. Either A. or B.

Explanation

The correct answer is Either A. or B..

2697Electrical EngineeringMedium

If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens________?

Athis will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed

Bthis will make armature to take heavy current, possibly burning it

Cnothing will happen to the motor

Correct answer

A. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed

Explanation

The correct answer is this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed.

2698Electrical EngineeringMedium

Which of the following primary cells has the highest voltage________?

ACarbon-zinc

BMercury

CLithium

DManganese-alkaline

Correct answer

C. Lithium

Explanation

The correct answer is Lithium.

2699Electrical EngineeringMedium

The effects of EMI can be reduced by________?

ASuppressing emissions

BReducing the susceptibility of the receptor

CReducing the efficiency of the coupling path

DAll of these

Correct answer

D. All of these

Explanation

The correct answer is All of these.

2700Electrical EngineeringMedium

Power factor of a synchronous motor is unity when________?

Anone of the above

Bthe armature current is maximum

Cthe armature current is minimum

Dthe armature current is zero

Correct answer

C. the armature current is minimum

Explanation

The correct answer is the armature current is minimum.

If two sine waves of the same frequency have a phase difference of JT radians, then________?

Anone of the above

Bboth will reach their maximum values at the same instant

Cwhen one wave reaches its maxi¬mum value, the other will reach its minimum value

Dboth will reach their minimum values at the same instant

Correct answer

C. when one wave reaches its maxi¬mum value, the other will reach its minimum value

Explanation

The correct answer is when one wave reaches its maxi¬mum value, the other will reach its minimum value.

If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens________?

Athis will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed

Bthis will make armature to take heavy current, possibly burning it

Cnothing will happen to the motor

Correct answer

A. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed

Explanation

The correct answer is this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses D. motor will run at very slow speed.