electrical engineering MCQ Test

electrical engineering MCQ Test
Engg Multiple Choice Questions
Electrical Engineering objective questions MCQ for graduate Engineer

1. The frequency of an LC circuit of a tuned base- tuned emitter type of coupled oscillator having resonant frequency of crystal as a is
(a) slightly less than ω
(b) equal to ω
(c) slightly more than ω
(d) at least 2 ω

Ans:-A


2. In an operational amplifier the bandwidth (B) in terms of rise time (t) is given ’by’
(a) 0.35 / tr
(b) 1 / 0.35 tr
(c) 0.35 tr
(d) tr / 0.35

Ans:-B


3. The figure of merit of a logic family is given by the product of
(a) gain and bandwidth
(b) propagation delay time and power dissipation
(c) fanout and propagation delay time
(d) noise margin and power dissipation

Ans:-A



4. Match List I with List II and select the correct answer using the codes given below the lists: List I
(Boolean statements is true)
A. AØB=O
B. A+B=O
C. A .B=O
D. AØB=l
List II
(Conditions under which)
1. A≠B
2. A=B
3. A=l and B=l
4. A=l and B=O
Codes:
A B C D
(a) 1 2 4 3
(b) 2 3 4 1
(c) 1 3 2 4
(d) 2 4 1 3

Ans:-C




5. For an energy signal g(t) and its time-shifted version g (t- r), the
(a) amplitude spectra are identical and their phase spectra are also identical
(b) amplitude spectra are identical but their phase spectra are different
(c) amplitude spectra are different but their phase spectra are identical
(d) amplitude spectra are different and their phase spectra are also different

Ans:-B


6. If the number of bits in a PCM system is increased from ii to rn+ 1, the signal-to-quanhisation noise ratio will increase by a factor
(a) (n+1) / n
(b) (n+1)2/n2
(c) 2
(d) 4

Ans:-B


7. A 600 Hz signal is sampled at a rate of 1000 samples per second. The frequency components of sampled signal will consist of
(a) 400 Hz and 600 Hz
(b) 400 Hz, 600 Hz and 1200 Hz.
(c) 600 Hz, 800 Hz, 1000 Hz and. 1200 Hz
(d) 600 Hz, 1000 Hz, 1200 Hz and 1400 Hz

Ans:-A



8. Consider the following statements regarding colour television:
1. Only chrominance signals occupy the full bandwidth.
2. Only luminance signals occupy the full bandwidth.
3. All the three signals occupy the full bandwidth.
4. The bandwidths of both the chrominance signals are equal
5. The bandwidth of luminance signals is smaller than that of the chrominance signals.
Of these statements:
(a) 1 and 4 are correct
(b) 2 alone is correct
(c) 3 and 4 are correct
(d) 5 alone is correct

Ans:-A


9. Instrument Leading System (ILS) and Ground Controlled Approach (GCA) are aircraft landing systems, wherein
(a) both use radar units on the ground
(b) both use special receivers on board the aircraft
(c) ILS uses special receivers in the aircraft and GCA uses radar units on the ground
(d) ILS uses radar units on the ground and GCA uses special receivers on the ground

Ans:-D


10. The standard test tone for audio portion of CCIR circuits is
(a) 0 d B m at 1000 Hz
(b) —3OdBmat800Hz
(c) 0 d B m at 400 Hz
(d) —3OdBmat400Hz

Ans:-A


11. In dc machine, the field system has to be provided on stator unlike synchronous machines wherein it could be on any member, because
(a) it reduces field structure iron losses
(b) it gives more uniform air-gap flux distribution
(c) commentator action is not possible otherwise
(d) dc machines are comparatively low rating machines

Ans:-D



12. In a dc generator operating on load with its brushes on the geometrical neutral axis (GNA), the magnetic neutral axis (MNA) is shifted in the direction of rotation
Now, if the brushes are given a lead of 90° (electrical), then the MNA will
(a) shift forward by 90°
(b) shift forward by more than 90°
(c) shift forward by less than 90
(d) coincide with the GNA

Ans:-D




13. A cumulatively compounded dc motor runs at 1000 rpm at no-load. On full load, the flux increases by 10%, whereas the full load drop in the combined resistance of the armature and series field is 5% Neglecting magnetic saturation, the full load speed will be nearly
(a) 863 rpm
(b) 909 rpm
(c) 1000rpm
(d) 1050rpm

Ans:-C


14. A dc over compound generator is supplying power to an infinite bus. If the prime mover is accidentally cut off, the dc machine will
(a) stop running
(b) run as cumulatively compounded motor in reverse direction
(c) run as differentially compounded motor in reverse direction
(d) run as differentially compounded motor in same direction

Ans:-C


15. Match List I with List II and select the correct answer using the codes given below the lists:
List I
(Load pf)
A. Zero leading
B. Unity
C. Zero lagging
D. Zero with armature terminals suddenly short-circuited
List II
(Nature of armature flux in an alternator)
1. Demagnetising
2. Magnetising
3. Cross magnetizing
4. Initially constant, demagnetizing
Codes:
A B C D
(a) 1 2 4 3
(b) 2 3 1 4
(c) 4 3 1 2
(d) 2 1 3 4

Ans:-B


16. A dc shunt motor is run under the following conditions:
1. Normal voltage with no additional resistance in armature or field circuits.
2. 50% normal voltage with no additional resistance in armature or field circuits.
3. Normal voltage with a small external resistance in the armature circuit of a value equal to the armature resistance.
4. Normal speed of the motor would increase in the sequence
(a) 1,2,3,4
(b) 1,4,3,2
(c) 2,1,4,3
(d) 2,3,1,4

Ans:-B


17. Consider the following statements about a three- phase synchronous generator synchronized to an infinite bus when its mechanical input is increased gradually with field current held constant:
1. The power factor of the current supplied becomes more lagging.
2. The power factor of the current supplied improves.
3. The power factor remains unity.
4. The load angle is increased.
Of these statements:
(a) 1 alone is correct
(b) 2 alone is correct
(c) 2 and 4 are correct
(d) 3 and 4 are correct

Ans:-A


18. Which of the following will change in a three- phase synchronous motor, as a consequence of excitation variations?
1. Pull-out torque
2. Torque angle
3. Magnitude and power factor of stator current
4. Output power
Select the correct answer using the codes given below:
Codes:
(a) l and 3
(b) 2 and 4
(c) 2,3 and 4
(d) 1, 2 and 3

Ans:-B


19. Following a sudden short-circuit at the terminals of a 3-phase unloaded synchronous generator, the initial effect of the pole-face damper winding, is to
(a) establish the armature flux through the direct-axis magnetic circuit of the machine
(b) allow only partial linkage of the armature flux with the main field winding
(c) confine the armature flux to completely link the damper winding
(d) Repel the armature flux and confine it to the leakage flux path in the air-gap.

Ans:-C






20. Consider the following statements about single- phase reluctance motor:
1. The starting torque is a function of rotor position.
2. The torque developed at sub synchronous speeds varies sinusoidally.
3. Starting is asynchronous but running is synchronous.
4. It pulls synchronism on switching on dc excitation.
Of these statements:
(a) 1, 2 and 3 are correct
(b) 1, 3 and 4 are correct
(c) 2, 3 and 4 are correct
(d) 1 and 4 are correct

Ans:-D