Electrical engineering objective questions

Electrical engineering objective questions and answers for Various Competitive Exams

1.A 10 V battery with an internal resistance of 1 Ohms is connected across a non-linear load whose v-i

characteristic is given by 7 _i = v² + 2v.
The current delivered by the battery is
(a) 2.5A
(b) 5A
(c)6A
(d)7A
2. A Voltage V ^–is applied to an ac circuit resulting in the delivery of a current I^–. Which of the
following expression would yield the true power delivered by the source ?
1. Real part of V ^–I^–
2. Real part of VI
3. I ²times the real part of V ^–I^–

Select the correct answer using the bodes given below:
Codes:
(a) 1 alone
(b) 1 and 3
(c) 2 and 3
(d) 3 alone

3.The current through the current coil of a watt meter is given by, i = (1+2 sin wt) V and the voltage across the pressure coil is, v = (2 +3 sin 2 wt) V The wattmeter will read
(a) 8.00W
(b) 5.05
(c) 2.0W
(d) 1.0W

4. A 3-phase, 3-wire supply feeds a load consisting of three equal resistors connected star. If 01w of the
resistors is open circuited, then the percentage reduction in the load will be
(a) 75
(b) 66.66
(c) 50
(d) 3.33

5. Two identical coils of negligible resistance, when connected in series across a S0Hzfixed voltage source, draw a current of 10 A. When the terminals of one of the coils are reversed, the current drawn is 8A. The coefficient of coupling between the two coils is
(a) 1/100
(b) 1/9
(c) 4/10
(d) 8/10

6. Swamping resistance is a resistance which is added to the moving coil of a meter to
(a) reduce the full – scale current
(b) reduce the temperature error
(c) increase the sensitivity
(d) increase the filed strength

7. A high frequency as signal is applied to a PMMC instrument. If the rms value of the ac signal is 2 V then the reading of the instrument will be ?
(a) zero
(b) 2 V
(c)3.2V
(d)4.2V

8. The resistance of a shunt for a precision grade ammeter can be best measured by
(a) De Sauty bridge
(b) Scherring bridge
(c) Maxwell bridge
(d) Kelvin double bridge

9. Which one of the following has the highest accuracy?
(a) Standard resistance
(b) Standard inductance
(c) Standard capacitance
(d) Standard mutual inductance

10. An indicating instrument is more sensitive if its torque to weight ratio is
(a) much larger than unity
(b) of the order of unity
(c) much less than unity
(d) made deflection – dependent

11. The X- and Y- inputs of a CR0 are respectively V sin wt and -V sin wt. The resulting Lissajous
pattern will be
(a) a straight line
(b) a circle
(c) an ellipse
(d) a figure of eight

12. In a flux meter, the controlling torque is
(a) produced b weights attached to the moving coil
(b) produced by spring
(c) not provided at all
(d) provided by crossed coil mechanism

13. Dummy strain gauge is used in conjunction with the main strain gauge to
(a) calibrate the system
(b) compensate temperature effects
(c) improve sensitivity
(d) reduce strain on the main gauge

14. In a two-watt-meter method of measuring power, one of the watt meters is reading zero watts. The
power factor of the circuit is
(a) zero
(b) 1
(c) 0.5
(d) 0.8

15. half effect device can be used to
(a) multiply two signals
(b) divide one signal by another on an instantaneous basis
(c) add two signals
(d) subtract one signal from another

16. Doppler shift principle is used in the measurement of
(a) temperature
(b) frequency
(c) speed
(d) pressure

17. In distortion factor meter, the filter is used to suppress
(a) dc component
(b) odd harmonics
(c) even harmonics
(d) fundamentals

18. Which of the following measurements can be made with the help of a frequency counter?
1. Fundamental frequency of input signal
2. Frequency components of the input signal at least upto third harmonic
3. lime interval between two pulses
4. Pulse width.
Select the correct answer using the codes given below:
Codes:
(a) 1,3and 4
(b) 1,2and 3
(c) 2and 4
(d) 1 and 2

19. The bandwidth requirement of an FM telemetry channel is
(a) equal to that of an AM telemetry channel
(b) smaller than that an AM telemetry channel
(c) about 100 times that of an AM telemetry channel
(d) about ten times that of an AM telemetry channel

20. The recording head in a magnetic tape responds to
(a) electrical signal and creates a magnetic signal
(b) thermal signal and creates a magnetic signal
(c) magnetic signal and creates an electrical signal
(d) thermal signal and creates an electrical signal.

21. When the input to a system was withdrawn at t= 0, its output was found to decrease exponentially
from 1000 units to 500 units in 1.386 seconds. The time constant of the system is?
(a) 0.500
(b) 0.693
(c) 1.386
(d) 2.000

22. Consider the following statements regarding constructional features of synchros:
1. Synchro repeater has a three-phase stator and three-phase rotor.
2. Disc shaped rotor of the synchro control transformer offers a low reluctance to the magnetic path.
3. Synchro transmitter has a frictionless bearing.
Of these statements
(a) 1,2 and 3 correct
(c) 2 alone is correct
(b) 1 alone is correct
(d) 2 and 3 are correct

23. Which of the following motors would be suitable for use as servomotors?
1. Two-phase induction motor.
2. DC separately excited motor.
3. Single-phase capacitance start induction motor.
4. Universal motor.
5. Single-phase synchronous motors.
Select the correct answer using the codes given below:
Codes:
(a) 1,2,3,4 and 5
(c) 1,2and5
(b) 2,3,and4
(d) 1 and 5

The following items consists of two statements, one labelled the ‘Assertion A’ and the
other labelled the ‘Reason R’. You as to examine these two statements carefully and decided !f the Assertion A and the Reason R are individually true and f so, whether the Reason is a correct explanation of the Assertion. Select your answer to these items using the codes given below and mark your answer sheet accordingly:
Codes:
(a) Both A and R are true and R’is the correct explanation of A.
(b) Both A and Rare true but R IsNOT a correct explanaton of A.
(c) A is true but R is false.
(d) A is false but R is true.

24. Assertion (A) : The static magnetic field has zero divergence and non-zero curl.
Reason (R) : The static magnetic field satisfies the flux law.

25. Assertion (A) : A glazed ceramic insulator has a lower breakdown strength than an unglazed one.
Reason (R) : Glazing covers pores and cracks and makes the surface non-absorbent.

26. Assertion (A) : In a type II superconductor, the magnetization gradually decreases between two critical values of the applied field Hc1 and Hc2.
Reason (R) : In a type II superconductor, magnetic flux lines are pinned by microstructural imperfection.

27. Assertion (A) : In an alternating field of 10¹⁴Hz, the electrical conductivity of a metal is zero.
Reason (R) : As the electrons fail to respond to the fast changing electric field, there is no drift.

28. Assertion (A) Addition of boron to intrinsic or pure silicon in the proportion of one borom atom to
¹⁴silicon atoms increases the conductivity of pure silicon by a factor of 10 at room temperature.
Reason (R) : Addition of impurities to intrinsic semiconductors increases carrier mobility

29. Assertion (A) A network consisting of ‘n’ nodes and ‘e’ elements can b_e completely ana1sed from (e — n + 1) mesh equations or (n — 1) node equations.
Reason (R) : The number of mesh equations plus number of node equations is equal to the number of elements in the network.

30. Assertion (A) : The poles and zeros of a rectance function alternate on the s-plane.
Reason (R) : The plot of rectance functions as a function of frequency always has a positive slope.

31. Assertion (A) The state steady response of a linear network is termed ‘forced response’.
Reason (R) : The forcing function does not have any effect on the transient response of a linear system.

32. Assertion (A) A variance is dependent on the mean value of the set of data.
Reason (R) : Variance is the difference of the mean squared values and the square of the mean value of the set of data.

33. Assertion (A) : The vertical deflecting plates of a CRT are kept farther away from the screen as compared to the horizontal deflecting plates.
Reason (R) : This improves accuracy in measurements.

34. Assertion (A) When plant parameter uncertainties are present, the open-loop structure is potentially superior to the closed-loop structure.
Reason (R) : When feedback is employed, there is a possibility of additional noise or uncertainty in the measurement of the plant signals.

35.Consider the following statements:
In electrostatics, the equipotential surface is defined as the surface where
1. Electric field intensity is normal everywhere.
2. Electric field intensity is tangential everywhere.
3. No work is done in moving a charge over it
4. No charge is present
Of these statements
(a) 1 alone is correct
(b) 3 and 4 are correct
(c) 1 and 3 are correct
(d) 2 and 4 are correct

36. Tangential component of the electric field on a perfect conductor will be
(a) infinite
(b) zero
(c) same as the normals field component and 900 out of phase
(d) same as the normal component but 180° out of phase

37. Two conducting shells of radii r1 and r2 (r1 > r2) each with a charge ‘Q’ are placed far apart in uniform external electric field . The space surrounding each shell is filled with the same dielectric material In this situation, the
(a) shells will not experience any force
(b) shells will experience identical forces
(c) shells will radius r1 will experience a greater force
(d) shell with radius r2 will experience a greater force

38. The directivity of an isotropic antenna is
(a) zero
(b) less than unity
(c) unity
(d) infinity

39. Consider the following statements
For a uniform place electromagnetic wave
1. The direction of energy flows the same as the direction of propagation of the wave.
2. Electric and magnetic fields are in time quadrature.
3. Electric and magnetic fields are in space quadrature
Of these statements
(a) 2 alone is correct
(b) 1 and 2 are correct
(c) 1 and 3 are correct
(d) 3 alone is correct

40. For an air dielectric transmission line, it isfound that as the frequency is varies from 50MHz up ward, the current reaches a minimum at 50.01 MHz and then a maximum at 50.04 MHz. The distance of the location of the short-circuit from the generator will then be
(a) 10km
(b) 2.5km
(c) 1 km
(d) not determinable from the given data

Answers:

1	b
2	c
3	c
4	c
5	b
6	b
7	a
8	d
9	a
10	a
11	a
12	c
13	b
14	c
15	a
16	c
17	d
18	a
19	a
20	a
21	d
22	c
23	c
24	b
25	a
26	a
27	a
28	c
29	a
30	a
31	c
32	c
33	a
34	c
35	c
36	b
37	b
38	c
39	c
40	d