MPPKVVCL Electrical Sample Questions

Questions And Answers

1 For the scalar field u = x2 2 + y2 3 , magnitude of the gradient at the point (1,3) is

A) Ö 13/9

B) Ö 9/2

C) Ö 5

D) 9 2

Correct Answer C

2 A digital-to-analog converter with a full-scale output voltage of 3.5 V has a resolution close to 14m V. Its bit size is

Options

A) 4

B) 8

C) 16

D) 32

Correct Answer B

3 A single-phase half-controlled rectifier is driving a separately excited dc motor. The dc motor has a back emf constant of 0.5 V/rpm. The armature current is 5 A without any ripple. The armature resistance is 2W. The converter is working from a 280 V, single phase ac source with a firing angle of 80°. Under this operating condition, the speed of the motor will be

A) 339 rpm

B) 359 rpm

C) 366 rpm

D) 386 rpm

Correct Answer C

4 In relation to the synchronous machines, which one of the following statements is false?

A) In salient pole machines, the direct-axis synchronous reactance is greater than the quadrature-axis synchronous reactance

B) The damper bars help the synchronous motor self start

C) Short circuit ratio is the ratio of the field current required to produce the rated voltage on open circuit to the rated armature current

D) The V-curve of a synchronous motor represents the variation in the armature current with field excitation, at a given output power

Correct Answer C

5 The 8085 assembly language instruction that stores the content of H and L registers into the memory locations 2050H and 2051H, respectively, is

A) SPHL 2050H

B) SPHL2051H

C) SHLD 2050H

D) STAX 2050H

Correct Answer C

6 If E is the electric field intensity, Ñ(Ñ x E ) is equal to

A) E

B) | E |

C) null vector

D) zero

Correct Answer D

7 For the function f(x) = x2 e-x, the maximum occurs when x is equal to

A) 2

B) 1

C) 0

D) -1

Correct Answer B

8 Two wattmeters, which are connected to measure the total power on a three -phase system supplying a balanced load, read 10.5 kW and – 2.5 kW, respectively. The total powere and the power factor, respectively, are

A) 13.0 kW, 0.334

B) 13.0 kW, 0.684

C) 8.0 kW, 0.52

D) 8.0 kW, 0.334

Correct Answer D

9 The insulation strength of an EHV transmission line is mainly governed by

A) load power factor

B) switching over-voltages

C) harmonics

D) corona

Correct Answer B

10 For the equation, s3 – 4s2+ s + 6 = 0the number of roots in the left half of s-plane will be

Options

A) zero

B) one

C) two

D) three

Correct Answer C

11 A dc potentiometer is designed to measure up to about 2 V with a slide wire of 800 mm. A standard cell of emf 1.18 V obtains balance at 600 mm. A test cell is seen to obtain balance at 680 mm. The emf of the test cell is

A) 1.00V

B) 1.34V

C) 1.50V

D) 1.70V

Correct Answer B

12 High Voltage DC (HVDC) transmission is mainly used for

A) bulk power transmission over very long distances

B) inter-connecting two systems with the same nominal frequency

C) eliminating reactive power requirement in the operation

D) minimizing harmonics at the converter stations

Correct Answer A

13 A bipolar junction transistor (BJT) is used as a power control switch by biasing it in the cut-off region (OFF state) or in the saturation region (ON state). In the ON state, for the BJT

A) both the base-emitter and base-collector junctions are reverse biased

B) the base-emitter junction is reverse biased, and the base-collector junction is forward biased

C)the base-emitter junction is forward biased, and the base-collector junction is reverse biased

D) both the base-emitter and base-collector junctions are forward biased

Correct Answer D

14 The Q – meter works on the principle of

A) mutual inductance

B) self inductance

C) series resonance

D) parallel resonance

Correct Answer C

15 A 800 kV transmission line is having per phase line inductance of 1.1 mH/km and per phase line capacitance of 11.68 nF/km. Ignoring the length of the line, its ideal power transfer capability in MW is

Options

A) 1204 MW

B) 1504 MW

C) 2085 MW

D) 2606 MW

Correct Answer C

16 If the following program is executed in a icroprocessor, the number of instruction cycles it will take from START to HALT is

START MVI A, 14H ; Move 14H to register A

SHIFT RLC ; Rotate left without carry

JNZ SHIFT ; Jump on non-zero to SHIFT

HALT

A) 4

B) 8

C) 13

D) 16

Correct Answer C

17 A moving iron ammeter produces a full scale torque of 240 mNm with a deflection of 120° at a current of 10 A. The rate of change of self inductance (mH/radian) of the instrument at full scale is

Options

A) 2.0 mH/radian

B) 4.8 mH/radian

C) 12.0 mH/radian

D) 114.6 mH/radian

Correct Answer B

18 At an industrial sub-station with a 4 MW load, a capacitor of 2 MVAR is installed to maintain the load power factor at 0.97 lagging. If the capacitor goes out of serivce, the load power factor becomes

Options

A) 0.85

B) 1.00

C) 0.80 lag

D) 0.90 lag

Correct Answer C

19 The conduction loss versus device current characteristic of a power MOSFET is best approximated by

A) a parabola

B) a straight line

C) a rectangular hyperbola

D) an exponentially decaying function

Correct Answer A

20 If P and Q are two random events, then the following is TRUE

A) Independence of P and Q implies that probability (P Q ) = 0

B) Probability (P Q ) Probability (P) + Probability (Q)

C) If P and Q are mutually exclusive, then they must be independent

D) Probability (P Q ) Probability (P)

Correct Answer D

MPPKVVCL Electrical questions answers

http://p3.placement.freshersworld.com/placement-papers/

MPPKVVCL Selection process

1.Written test

2.Interview

a) The Eligible candidates shall have to undergo a written test comprising of questions in relevant branch of Engineering and General Aptitude (Logical Reasoning and General Knowledge).

b) The written test will be of 2 hours 30 minutes duration.

c) Date of written test 24th March 2013

MPPKVVCL electronics and electrical engineering model question for practice.This is only sample placement papers

1. To neglect a voltage source, the terminals across the source are

(A) open circuited

(B) short circuited (Ans)

(C) replaced by some resistance

(D) replaced by an inductor

2. Current I0 in the given circuit will be

(A) 10 A

(B) 3.33 A (Ans)

(C) 20 A

(D) 2.5 A

Solution : RT = 2 + 2 || [1 + (2 || 2)]

= 2 + 2 || (1 + 1)

= 2 + 2 || 2 = 2 + 1 = 3 ?

So I = 40 A

3

By current division I0 = 1 * 1 * 40 = 10 A

2 2 3 3

I0 = 3.33 A

3. In a resonant circuit, the power factor at resonance is

(A) zero

(B) unity (Ans)

(C) 0.5

(D) 1.5

4. In the given circuit voltage V is reduced to half. The current will become

(A) I/2 (Ans)

(B) 2 I

(C) 1.5 I

(D) I / ?R2 + (XL + XC)2

Solution : I a V if V reduced half current becomes I .

2

5. The function 3 s has

(s + 1) (s + 2)

(A) one zero, two poles (Ans)

(B) no zero, one pole

(C) no zero, two poles

(D) one zero, no pole

Solution : G (s) = 3s has one zero at s = 0 and two poles at s = – 1, – 2.

(s + 1) (s + 2)

6. One electron volt is equivalent to

(A) 1.6 * 10-10 J

(B) 1.6 * 10-13 J

(C) 1.6 * 10-16 J

(D) 1.6 * 10-19 J (Ans)

7. Which of the following is donor impurity element ?

(A) Aluminium

(B) Boron

(C) Phosphorous (Ans)

(D) Indium.

8. The diameter of an atom is of the order

(A) 10-6 m

(B) 10-10 m (Ans)

(C) 10-15 m

(D) 10-21 m

9. The following Figure represents

Image – BSNL- MB (J.T.O.) RE 2001 – Part A – Qno. 9

(A) LED (Ans)

(B) Varistor

(C) SCR

(D) Diac

10. If the d.c. valve of a rectified output is 300 V and peak to peak ripple voltage is 10 V, the ripple factor is

(A) 1.18%

(B) 3.33% (Ans)

(C) 3.36%

(D) 6.66%

Solution : rms value of output

= ?3002 + 102 = 300.166 V

Average value = 300 V

Form factor RMS value = 300.166 = 1.00055.

Average value 300

Ripple factor = ?(Form factor)2 – 1

= ?(1.0005)2 – 1 = 0.0333

= 3.33%.

11. Full wave rectifier output has ripple factor of

(A) 1.11 (Ans)

(B) 1.21

(C) 1.41

(D) 1.51

12. In a common base connection IE = 2 mA, IC = 1.9 mA. The value of base current is

(A) 0.1 m (Ans)

(B) 0.2 mA

(C) 0.3 mA

(D) zero

Solution : IE = 2 mA IC = 1.9 mA

Ib = IE – IC = (2 – 1.9) = 0.1 mA.

13. For the action of transistor the base region must be

(A) P-type material

(B) N-type material

(C) very narrow (Ans)

(D) highly doped

14. Compared to a CB amplifier the CE amplifier has higher

(A) current amplification

(B) output dynamic resistance

(C) leakage current

(D) input dynamic resistance

(E) all of the above (Ans)

15. When a transistor is biased to cut-off its Y is

(A) 0.5

(B) 0

(C) 1.0 (Ans)

(D) 0.8

16. An ideal voltage amplifier should have

(A) Ri = 0, R0 = 0

(B) Ri = 0, R0 = ¥

(C) Ri = ¥, R0 = 0 (Ans)

(D) Ri = 0, R0 = ¥

17. Barichausen criterion for sustained oscillator is

(A) A? = 1 Ð00 (Ans)

(B) A? = 0

(C) A? = 1 Ð1800

(D) A = 1/??

18. The value of plastic capacitance for a triode may range from

(A) 2 ?F to 12 ?F

(B) 20 ?F to 120 ?F

(C) 2 pF to 12 pF (Ans)

(D) 20 pF to 120 pF

19. A colpitts oscillator uses

(A) tapped coil

(B) inductive feedback

(C) tapped capacitance (Ans)

(D) no tuned LC circuit

20. A typical frequency for a RC feedback oscillator is

(A) 1 KHz (Ans)

(B) 100 MHz

(C) 1000 MHz

(D) 1 GHz