Basic Electrical/Transformer/Page-01

This blog is an attempt to help you familiarize  electrical engineering competitive exam questions and answers.
The standard for the exam will be expect of an engineering holder.
This question paper may include the  following type of questions

• Direct questions contains - direct Theory and definition questions
• Problems - apply Mathematical formula for the solution.
• Advanced level questions include Design & application level questions
• Tricky or twisted question

1. Transformers are rated in

     (a)kV     (b)kW        (c) kWH       (d)KVA

Ans: d

2. The  transformer works on the principle of
     (a) static induction                  (b) self induction           (c) mutual induction    (d) both a and b
Ans: d

3. Transformer is used to change the vales of
          (a) Frequency (b) voltage (c) power (d)power factor
Ans:b

Tips: Transformer is used to change the values of  voltage and current. Transformer does not change the frequency and wave form.

4. A transformer provides a path for magnetic flux of
     (a) high conductivity (b) high reluctance (c) low reluctance (d) low conductivity
Ans:c

5.The emf induced in a coil depends on
    (a) the number of its turns
     (b) the change of flux linked with it
     (c)the time taken to change the flux
    (d)all of the above
Ans: d

IM/Measuring instruments /Level-1/Practice test -01

1.   1.T he sensitivity of a voltmeter using 0 to 5 mA meter movement is

A)     50 ohm/volt

B)     100 ohm/volt

C)     200 ohm/volt

D)     500 ohm/volt

Ans: D)200 ohm/volt  (1/I_fsd =sensitivity )

2.   

2.2.Which of the following meter is most suitable for measuring radio frequency currents?

A)     Moving-coil meter

B)     Moving-iron meter

C)     Thermocouple meter

D)     VTVM

Ans: C) Thermocouple meter.

Audio frequency measurements VTVM by using rectifier

3.   

3.3. At high frequency the accuracy of all the measuring meters

A)     Increases

B)     Decreases

C)     Remains the same

D)     Depends upon the type of meter

Ans:B) Decreases

4.   4.Megger in its operation in based upon

A)     Moving coil meter

B)     Moving coil meter

C)     Dynamic –meter

D)     Electrostatic meter

Ans: A) Moving coil meter ; It consist of  hand driven generator and a moving coil meter(two coil windings – pressure coil and current coil )

5.   

5.5. Damping provides

A) breaking action on a meter pointer

B) good accuracy

C) starting torque on the meter pointer

D) counter torque to deflection torque

Ans: A) breaking action on a meter pointer

Data Structure/Level-1/Paper-01

1. When new data are to be inserted into a data structure, but there is not available space; this situation is usually called ….

A. Underflow

B. overflow

C. houseful

D. saturated

Ans:  B. overflow

2 . Which is/are the application(s) of stack

A) Function calls

B) Large number Arithmetic

C) Evaluation of arithmetic expressions

D) All of the above

Ans: D) All of the above

3. which of the following data structure is non linear type?

A) String

B)Lists

C) Stacks

D) Graph

Ans: D) Graph

4.which of the following data structure is linear type?

A) Graph

B) Trees

C) Binary Tree

D) Stack

Ans: D) Stack

5. Which of the data structure can't store the non-homogeneous data elements?

A) array 

B) Records

C) Pointers

D) Stacks 

Ans: A) array 

__________________________Points to remember______________________________

Types of Data structures:

There are two types of data structure
i) Linear  (Stack,liked list,queue )
ii) Nonlinear  (eg. Graph, Tree)

The more commonly used data structures include lists,arrays,stacks ,queues,heaps, trees and graph.

Arrays:

The simple type of data structure is linear array. A linear array  is list of a finite number of n of similar data elements .

Linked list:

A list is an ordered structure of data.It is often used to store objects that are to be processed sequentially . A list can be used to create a queue.

 Stack:

A stack is a last in, first out (LIFO) data structure. Items are removed from a stack in the reverse order from the way they were inserted

                There are two stack errors that can occur:

                                     Underflow: trying to pop  an empty stack

                                      Overflow: trying to push onto an already full stack

 Queue:

A queue is a first in, first out (FIFO) data structure. This is accomplished by inserting at one end (the rear) and deleting from the other (the front).Items are removed from a queue in the same order as they were inserted.The process to add an element into queue is called Enqueue and the process of removal of an element from queue is called Dequeue.

 Deque 

 A deque is a double-ended queue. Items can be inserted and removed at either end. Deques (pronounced deck) are not heavily used. Deque" is not to be confused with dequeueing ( a queue operation)

Trees:

Data frequently contain a hierarchical relationships between various elements . The data structure which reflects this relationships is called a rooted tree graph or a tree.

Graph : 

Graphs are data structures rather like trees. Graphs often have a shape dictated by a physical or abstract problem . For example , nodes in  a graph may represent cities , while edges may represent airline flight routes between the cities . Nodes are traditionally called vertices

CONTENTS

BROAD BAND :

Small Form-factor Pluggable (SFP) Optical Transceivers

Broad Band Equipment

DSL Technology (MCQs)

IP address Basic concepts in networking 



BASIC ELECTRICAL

Basic Electrical/Electric Current/Level-0/Paper-01

Basic Electrical/Resistance/Level-1/Paper-02

Basic Electrical/Electrical circuits/Level-0/Paper-04

Basic Electrical/Network theorems/Set-1/Paper-02

Basic Electrical/Capacitance/Set-1/Paper-03 

Basic Electrical/Inductance/Level-0/Paper-01

COMPUTER SCIENCE

CS/Computer Generation/Level -0/Paper-01

ELECTRONICS ENGINEERING :

GENERAL SCIENCE:

X rays

GS & EL/X-rays/Level-0/Paper-01

Properties of X-ray

1. X rays are electromagnetic(EM) waves of very short wave length

2. They travel in straight lines with the velocity of light

3.They are invisible to eyes

4. Under suitable conditions , X-rays are reflected & refracted like ordinary light

5. They are not deflected by electric and magnetic fields.

Wave length=1Å

X-rays can penitrate throughbthe substances which are opaque to ordinary light eg: wood,flesh,thick paper,thin sheets of metals

6)They cause Fluorescence on many substanstances like barium,cadmium, tungstate, Zinc,sulphate etc.

7)X-rays can ionise a gas through which they pass

8) when X-rays are fall on certain metals ,they liberate photo electrons(photo electric effect)

9)when X-rays fall on heavy metals ,they produce secondary X-rays

10)X-rays have destructive effects on living tissues

(When they are exposed to human body , they cause reddening of the skin,sores and serious injuries to the tissues and gland .they can destroy white corpuscles of the blood)

Basic Electrical/Resistance/Level-1/Paper-02

Resistance is defined as the property of a substance due to which it opposes  the flow of electricity  through it.Unit ohm  Ω.

Laws of Resistance

(i) Resistance decreases with decrease in   its length, l.

(ii) Resistance decreases with increase in the cross-section A of the conductor.
     i.e. Thicker wire has   lower resistance.

(iii) Resistance depends on the nature of the material the conductor made of.

(iv) Resistance also depends on the temperature of the conductor.

 

          

where ρ is a constant depending on the nature of the material of the conductor and is known as                   its specific resistance or resistivity.Unit ohm-metre(Ω-m).

Conductance :

Conductance (G) is reciprocal of resistance.Unit  siemens (S).
 Earlier, this unit was called mho.

          

 Conductivity :

σ is called the conductivity or specific conductance of a conductor.

It is seen from the above equation that the conductivity of a material is given by

Hence, the unit of conductivity is siemens/metre (S/m).


Effect of Temperature on Resistance

• Insulators (such as paper, rubber, glass, mica etc.) are said to possess a negative temperature-coefficient of resistance 
• Semiconductors have a positive temperature co-efficient of resistance.
• Metals have a positive temperature co-efficient of resistance.
•  The effect of rise in temperature is to decrease the resistance of electrolytes,and partial conductors such as carbon.

Q1. A given wire is stretched to double its length. How much its resistance change ?

(1) resistance is same

(2) resistance becomes four times

(3) resistance becomes two times

(4) resistance becomes half times

Ans: 2
Hint:

After stretching the resistance changes but resistivity remains the same.
As volume of wire is constant so area and length are inversely proportional.

So if the length is doubled by stretching , area of cross section becomes halved.

After stretching wire length is doubled.New length is 2l .

.
Q2. Two cylindrical resistors, R1 and R2, are made of identical material. R2 has twice the length of R1 but half the radius of R1.

Solution:
The area of a circle is equal to the square of its radius times Pi.Relationship between the cross section  area of half the radius of R1 with R2.

Resistance is inversely proportional to the area of cross section.

EL Engg/Semiconductor Engineering/Level-1//Paper-01

1. In intrinsic semiconductors, number of electrons __________ number of holes. 

(a) Equal (b) Greater than (c) Less than (d) Can not define

Ans: (c) Less than

2. Fermi energy level for intrinsic semiconductors lies

(a) At middle of the band gap (b) Close to conduction band
(c) Close to valence band (d) None

Ans:(c) Close to valence band

3. Flow of electrons is affected by the following


(a) Thermal vibrations (b) Impurity atoms (c) Crystal defects (d) all

Ans: (d) all

4. Fermi level for extrinsic semiconductor depends on 

(a) Donor element (b) Impurity concentration (c) Temperature (d) All

Ans:(d) All

5. Fermi energy level for n-type extrinsic semiconductors lies 

(a) At middle of the band gap (b) Close to conduction band 

(c) Close to valence band (d) None

Ans: (b) Close to conduction band 

_______________________________SOLUTION___________________________________

5. Ans: (b) Close to conduction band.
The Fermi level lies in the middle of the forbidden gap.
Fermi level lies near valence band in P type and near conduction band in N type

General Science/Level-1/Set-1/Paper-01

1. Radiations infra-red region may be detected with the help of
a)barometer
b)bolometer
c)spectrometer
d)sonometer
Ans:B bolometer

2. Simple astronomical telescope consist of two
A)convex lenses
B)concave lenses
C)one convex lens and other concave lens
D)Plano convex lenses
Ans: a convex lensses

3.A yellow object when seen through a red glass appears as
A)yellow
B)red
C)white
D)black
Ans.d black

4.X rays are emitted when
A)high energy electrons hit a substance of low molecular weight
B)high energy electrons hit a substance of high molecular weight
C)low energy electons hit any substance
D)low energy electons hit a substance of high molecular weight
Ans:b

5. Which of the following can be deflected by a magnet?
A)radio waves
B)X rays
C)beta rays
D)ultra violet rays
Ans.B beta rays

EL/Power Amplifiers/Level-1/Set -1/Paper-01

1.Which of the push-pull amplifiers is presently the most popular form of the class B power amplifier?

A) Quasi-complementary

B)Transformer-coupled

C)Complementary-symmetry

D)None of the above

 Ans:A) Quasi-complementary

2. In a class C amplifier 

A) Efficiency and distortion both are maximum 

B) Efficiency and distortion both are minimum. 

C) Efficiency maximum but distortion minimum. 

D) Efficiency minimum but distortion maximum

3. High power efficiency of the push-pull amplifier is due to the fact 

A) Each transistor conducts on different cycles of the input. 

B) Transistors are placed in CE configuration. 

C) There is almost no quiescent collector current 

D) Low forward biasing voltage is required.

4. Which amplifier is commonly used as a frequency multiplier?

A) class A

B) class B

C) class C

D) all of the above

Ans:D) all of the above

Basic Electrical/Electric Current/Level-0/Paper-01

Q1. A perfect conductor has

(a) Zero conductivity

(b) unity conductivity

(c) infinite conductivity

(d) none of  the above

Ans:c

Q2. The conductivity of a conductor can be increasingly

(a) decreasing its temperature

(b) increasing its temperature

(c) decreasing its vibration

(d) increasing its vibration

Ans: a

Q3. Which of the following  are no-conductors of electricity ?

(a) Non-metal solids except carbon

(b) Air and most other gases

(c) Pure water and liquids

(d) All of the above

Ans:d

Q4. Unit of electrical conductivity

(a) mho/metre (b) mho/sq.m  (c)ohm/metre (d)ohm/sq.m

Ans:a

Q5.Resistance of a material always decreases I

(a) temperature of material is decreased

(b)temperature of material is increased

(c)number of free electrons available become more

(d)none of the above is correct

Ans:c

CS/Computer Generation/Level -0/Paper-01

Q1. Microprogramming is a designing of

(a)ALU (b)CPU (c)ROM  (d)Control Unit

Ans: d

Q2.Which of the following code used in present day computing was developed by IBM Corporation?

A) ASCII

B) Hollerith Code

C) Baudot Code

D) EBCDIC Code

Ans:d

Q.3 What difference does the 5th generation computer have from other generation computers?

(a) Technological advancement

(b) Scientific code

(c) Object Oriented Programming     

(d) All of the above

(e) None of the above

Ans:d

Q4. Which of the following memory is responsible for co-ordinating various operations using timing signals?

(a) ALU    (b) Control Unit (c) Memory Unit (d) I/O Unit

Ans:b

Q5. Keyboard Converts typed in character to___________code

(a)EBCIDIC  (b) ASCII (c) None of these

Ans:b