(Solved) J. B. Gupta important questions from model test paper with solution

-

Important questions of JB Gupta book Model Test Paper 2 :

(We are working to provide detailed solutions of each question. We are updating this page.)


Question 1 :

In a magentic material, hysteresis loss takes place primarily due to 

(a) rapid reversals of its magnetisation 

(b) flux density lagging behind magnetis ing force 

(c) molecular friction 

(d) its high retentivity

Ans: D

 

Question 2 :

On which of the following factors does the resolution of a potentiometer depend?

(a) Size of wire 

(b) Type of contact

(c) Composition of wire material 

(d) Shape of wire cross-section

Ans: A

 

Question 3 :

The braking retardation is usually in the range

(a) 0.15 to 0.30 km phps 

(b) 0.30 to 0.6 km phphs 

(c) 0.6 to 2.4 km phps 

(d) 3 to 5 km phps 

(e) 10 to 15 km phphs

Ans: D


Question 4 :

Which of the following methods is used for reduction/elimination of harmonic torques?

(a) Chording

(b) Integral slot windings

(c) Skewing

(d) Increase in air gap length 

(e) All of the above

Ans: E


Question 5 :

A permanent magnet 

(a) attracts some substances and repels others

(b) attracts all paramganetic substances and repels others

(c) attracts only ferromagnetic substances (d) attracts ferromagnetic substances and repeals all others

Ans: A


Question 6 :

In order to convert the angular position of a shaft into an electric signal, which of the following electromagnetic transducers can be used?

(a) A.C. servemotor

(b) Thermocouple 

(c) Rotary LVDT

(d) Synchrous

Ans: D


Question 7 :

Which of the following motors one will choose to drive the rotary compressor? 

(a) D.C. shunt motor

(b) D.C. series motor

(c) Universal motor

(d) Synchronous motor

Ans: D


Question 8 :

A pilot exciter is provided on generators for which of the following reasons ?

A. To excite the poles of main exciter

B. To provide requisite starting torque to main exciter

C. To provide requisite starting torque to generator

D. None of the above

Ans: A


Question 9 :

A parallel resonant circuit can be used 

(a) as a high impedance 

(b) to reject a small band of frequencies

(c) both (a) and (b)

(d) to amplify certani frequencies

Ans: C


Question 10 :

Current density in the rotor bars of an induction motor may be taken between

(a) 1.5 to 2.5 A/mm² 

(b) 3 to 4 A/mm²

(c) 4 to 7 A/mm²

(d) 8 to 10 A/mm²

Ans: C


Question 11 :

The property of a coil carrying a changing current to induce a counter e.m.f. is called

(a) self inductance

(b) mutual inductance

(c) series aiding inductance

(d) series opposing inductance

Ans: A


Question 12 :

Wien bridge is usually used for the meas urement of which of the following?

(a) Frequency 

(b) Capacitance 

(c) Resistance 

(d) Inductance

Ans: B


Question 13 :

An A/D converter uses for reference purposes

(a) a flip-flop 

(b) a sawtooth generator

(c) d.c. voltage 

(d) set of keys

Ans: B


Question 14 :

Hall effect can be used to measure

(a) carrier concentration

(b) electric field intensity 

(c) magnetic field intensity

(d) none of the above

Ans: C


Question 15 :

Generally....flip-flops are used in shift

registers 

(a) D

(b) T

(c) SR

(d) JK

Ans: D


Question 16 :

To increase the Q-factor of an inductor it is wound with

(a) longer wire 

(b) coiled coil wire

(c) thicker wire 

(d) thinner wire

Ans: C


Question 17 :

The function y(s) :(2s² + 2s + 1)/(s² +2s +2) is a

(a) Hurwitz polynomial

(b) positive real function

(c) not a positive real function

(d) none of the above

Ans: B

Degree of numerator is not exceeding degree of denominator by more than unity. Here degree of numerator and denominator are same. So it is positive real function.


For any queries in solutions please comment below. 



Comments

Post a Comment

Popular posts from this blog

(Solved) A step down DC chopper has a resistive load of R = 15 ohm and input Vdc = 200 V. When the chopper remain ON, it's voltage drop is 2.5V. The chopper frequency is 1 kHz. If the duty cycle is 50%, determine: a) Average output voltage b) RMS output voltage c) Chopper efficiency d) The effective input resistance of the chopper

-
Image
Question:   A step down DC chopper has a resistive load of R = 15 ohm and input Vdc = 200 V. When the chopper remain ON, it's voltage drop is 2.5V. The chopper frequency is 1 kHz. If the duty cycle is 50%, determine:  a) Average output voltage  b) RMS output voltage  c) Chopper efficiency  d) The effective input resistance of the chopper Answer: We can get answers directly by applying relevant formulas as shown below.  (a) Average output voltage = 98.75 V (b) RMS output voltage = 139.6536 V (c) Chopper efficiency = 98.75% (d) The effective input resistance = 30.3799 ohm Additional information : Waveforms for step down chopper are shown below : For any queries regarding above solution please comment below. Thank you! 
Read more

(Solved) When a reverse bias is applied to a germanium PN junction diode, the reverse saturation current at room temperature is 0.3m A. Determine the current flowing in the diode when 0.15v forward bias is applied at room temperature.

-
  Question : When a reverse bias is applied to a germanium PN junction diode, the reverse saturation current at room temperature is 0.3m A. Determine the current flowing in the diode when 0.15v forward bias is applied at room temperature. Solution : Given Io = 0.3 * 10-6A and VF = 0.15v The current flowing through the PN diode under forward bias is I = Io (e^(40VF) -1) for germanium diode = 0.3 * 10^(-6) (e^(40*0.15) -1) = 120.73mA. For any further queries please comment below.  
Read more

(Solved) An LVDT is connected to an amplifier of gain 250 the output terminals of which are connected to a 5 V voltmeter. The meter's scale can be read to 1/5th of a division and has 100 divisions in all. Given that a core displacement of 0.5 mm provides an output of 2 mV from the LVDT, find, 1. The sensitivity of the LVDT 2. The sensitivity of the whole system 3. The resolution of the instrument in centimeters

-
Image
 Question : An LVDT is connected to an amplifier of gain 250 the output terminals of which are connected to a 5 V voltmeter. The meter's scale can be read to 1/5th of a division and has 100 divisions in all. Given that a core displacement of 0.5 mm provides an output of 2 mV from the LVDT, find,  1. The sensitivity of the LVDT  2. The sensitivity of the whole system  3. The resolution of the instrument in centimeters Explanation : (a) Sensitivity of LVDT = Output voltage /displacement  Sensitivity of LVDT = 2mV/0.5 mm = 4 mV/mm (b)Sensitivity of whole setup = amplification factor*sensitivity of LVDT  Sensitivity of whole setup = 250*(4 mV/mm) = 1000 mV/mm (c) The resolution of the instrument in centimeters = minimum voltage that can be read by instrument /sensitivity of whole setup  There are 100 divisions to measure upto 5V.  So 1 division can read 5/100 = 0.05V Scale can read 1/5 of a division.  So minimum voltage that can be read = 0.05/5 ...
Read more