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Answers for E.C.E 4

Below are the answers for questions asked in E.C.E 4

  1. Speech amplifiers are mainly used as Class A amplifiers.
  2. In a low level AM system, amplifier following the modulated stage must be a Linear Device.
  3. Linearity
  4. If the modulation index is more than 100% then modulated carrier signal will periodically reduced to zero. This will not effect the working of transmitter but the receiver will produce a distorted output.
  5. Modulation is the process of converting one or more property of a high frequency Carrier wave according to the input signal. 
  6. -
  7. Class C
  8. -
  9. A linear amplifier
  10. 0 to 1
  11. 100 watts
  12. With the help of formula of capacitance of parallel plates i.e. 

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Learn Maxwell Equations

Maxwell equations are basically a relationship between electricity and magnetism. These are 4 basic equations represents Maxwell equations :-

Now let's talk about these equations one by one

Equation no. 1 

This law states that flow of electric field associated with a particular region is equal to the total charge present in that region divided by a constant( permittivity of free space ).

Equation 2 

It stats that magnetic field remains constant and for a given space it remains zero.

Equation 3

Also Known as Faraday's Law of induction.

Equation no.4

Also known as Ampere's Law as amended by Maxwell, and also known as

∇×H = J +

Symbols of Different Transistors

There are mainly 2 families of Transistor i.e. Bipolar and Uni-polar Transistors.
Bipolar Transistors have 2 kind of carriers both holes and electrons while Unipolar Transistors 
have only single carrier either Hole or electrons.

Below are the symbols for BJT, FET, MOSFET, Duel gate MOSFET, Inductive channel MOSFET and Single connection Transistor.

fig a - BJT
fig b - FET
fig c - MOSFET
fig d - Duel gate MOSFET
fig e - Inductive Channel MOSFET
fig f - Single connection Transistor


Network Theorems

Superposition Theorem

The response in any element of linear, bilateral network containing more than one source is the sum of the response produced by the sources each acting independently.
The superposition principle is only applicable to linear networks and systems.
The superposition theorem does not apply to the power as power is proportional to square of the current which is not a linear function.
  1. Select a single source. Short the other voltage sources and open the current source, if internal impedance's are not known. If known than replace them by their internal impedance.
  2. Find out the current through or the voltage across the required element, due to the source under consideration.
  3. Repeat the above step for all the sources.
  4. Add all the individual effect produced by individual sources to obtain the total current in or voltage across the element.

Thevenin's Theorem

Any combination of linear bilateral circuit elements and active sources, regardless of the connection and complexity, connected to a given load Zmay be replaced by a single two terminal network consisting of a
Single voltage source of VTH and a single impedance Zeq in the series with the voltage source, across the two terminals of the load ZL.
1.       Remove the branch impedance, through which current is required to calculate.
2.       Calculate the voltage across the open circuited terminals. This voltage is Thevinin’s equivalent voltage VTH .
3.       Calculate the equivalent impedance Zeq as viewed through the two terminals of the branch from which current is to be calculated by removing that branch impedance and replacing all the independent sources by their internal impedance.
4.       The required current through the branch is given by, I = VTH / ZL + Zeq .

Norton’s Theorem

Any combination of linear bilateral circuit elements and active services regardless of the connection or complexity, connected to a given load ZL can be replaced by a simple two terminal network consisting of a single current source of IN and a single impedance Zeq in parallel with it, across the two terminals of the load ZL .
1.       Short the branch through which the current is to be calculated.
2.       Find out the current through this short circuited branch. This current is nothing but the Norton’s current IN.
3.       Calculate the equivalent impedance Zeq as viewed through the two terminals of interest by removing the branch impedance and making all the independent sources inacticve.
4.       The current through the branch of interest is  I = IN * Zeq / ZEQ + ZL.


Different Logic Gates

Logic gates are the general purpose electronics devices which have a specific o/p state for diffferent combinations of input.

Different types of Logic gates:-

1. AND Gate

Truth table     


Relationship between inputs and output

Output = A and B

2. OR Gate


Truth table


Relationship between inputs and output

Output =    A or B


3. NOT gate


Truth Table
Relationship between inputs and output

Output =  Not A


4.NOR gate


Truth Table
Relationship between inputs and output

Output = Not(A OR B)


5.NAND gate


Truth table
Relationship between inputs and output

Output =  Not (A AND B)


6. XOR gate


Truth Table
Relationship between inputs and output

Output  =   [ A AND (NOT B) ] OR [ (NOT A) AND B ]


7. XNOR gate


Truth Table
Relationship between inputs and output

Output = [ A AND B] OR [ (NOT A) AND (NOT B)]


Countable and Non-Countable nouns

Countable nouns are those which can be counted, they also have singular as well as plural forms.
Countable nouns are used with a,an,the,many,few,fewer,number,this,that,every,each, neither,either,those,these,some,any,enough
For example - She made fewer mistakes in the match today

While non-countable or Mass nouns are those which can't be counted and sometime they do not have any plural form.
Non-countable nouns are used with much,less/lesser,this,that,some,any,enough,amount of
For example - Arun have less money than suresh

Some of the nouns can be used as both Countable and non countable ones. It just depends upon how we are using them.
For example-  he got into trouble(non-countable)
                       he had many troubles(countable)

the usage of 's and s'

Apostrophe ( ' ) and letter ( s ) is used to make a noun possessive.

For example - That car is amit's
                        The men's hockey match is tomorrow.

  • A singular noun can use 's and s' for same effect. 

For example - The car's speed is slow               correct
                        The cars' speed is slow               correct

  • A Plural ending with s takes apostrophe( ' ) to become possessive.

For example - The new buses's are fast              correct
                        The new buses's are fast              incorrect

Common mistakes in Grammer

Terms in Linear Algebra

Some important terms related in Linear algebra

  • Nul matrix A matrix in which all elements are zero is called Null matrix.
  • Row matrix A matrix with 1 row and any no. of column is called Row matrix.
  • Column matrix A matrix with 1 column and any no.of row is called column matrix
  • Square matrix A matrix having equal no. of rows and columns is called Square matrix.
  • Unit matrix A Square matrix in which all diagonol elements are 1 and all non diagonal elements are 0 is called Unit matrix.
  • Diagonal Matrix A Square matrix in which all diagonal elements are non zero and non diagonal matrix are 0 is called Diagonal matrix.
  • Scalar matrix A diagonal matrix with all diagonal elements are a scalar is called Scalar matrix.
  • Symmetric Matrix A matrix which satisfy the relation ,,    aij = aji 
  • Skew-symmetric matrix A matrix which satisfy the relationship ,,aij = -aji
  • Triangular matrix A matrix whose elements below or above the leading diagonal are zero are called triangular matrix.
  • Transpose of a matrix A matrix obtained after exchanging the rows and columns of a matrix is called transpose of a matrix. It is donated as AT
  • Orthogonal matrix A matrix which satisfy this relationship,,,,, AT.A= 1
  • Conjugate Matrix A matrix obtained by the complex conjugate of a matrix A is called Conjugate matrix. 


Questions on electronics and communication engineering - 4

E.C.E 4

These questions depends upon the Topic 'Amplitude Modulation'

  1. Speech amplifiers are usually operated as?
  2. In a low level AM system, amplifiers following the modulated stage must be?
  3. Low level modulating AM transmitter shows which property?
  4. What happens when modulation index is more than 100% in AM?
  5. What is the core function of a modulator?
  6. Plot carrier transmission contains?
  7. Which kind of modulation amplifiers are used in AM transmitter?
  8. What is the main requirement for a long wave AM broadcast transmitter?
  9. In a low level AM transmitter, the amplifier following the modulated state must be.
  10. Modulation index lies between?
  11. The power rating of a radio transmitter is around?
  12. How we can determine the frequency of the piezoelectric effect?

E.C.E 1
E.C.E 2
E.C.E 3

Answers For E.C.E - 3

Answers of E.C.E - 3 Questions

1. Rhombic Antenna

2. Smaller the beam-width angle, higher the directivity.

3. There are more than one driven elements in a driven array.

4. The effective length of a antenna is always greater than it's physical length.

5. Earthmat is used to ensure: -
  • Provision of earth from the antenna
  • Improvement of radiation patteren
  • impossibility of good ground connection
6.  2.15 db

7. The induced voltage will experience 2 maxima and 2 null.

8. as a UHF receiving antenna.

9. 2

10. We use counterpoise to reduce: -
  • Rockiness of ground connection
  • Difficulty of a good ground connection
  • Provision of earth from antenna.
11.  Top loading can be done by increase effective height.

12. Input impedance of folded dipole antenna is 280 ohms.

13. Unipolar antenna is best for low frequency transmission.

14.An antenna behave as a resonant circuit, when it's length is a integral multiple of  ʎ/2

15. An half wave dipole produce Broadside pattern.

16. The range will increase by the factor of  21/2

17. 1/2r

18. Loop antenna is commonly used for direction finding.


19. A parabolic antenna is commonly used at 5000 MHz. 

20.  The radiation pattern of Parabolic antenna is highly directional.

Answer for E.C.E 3 Questions

E.C.E 1 Questions
E.C.E 2 Questions


Questions on electronics and communication engineering 3

E.C.E. Questions -3

The following questions depends upon Antenna and it's application
  1. Give example of non-resonant antenna.
  2. What is the Relationship between Beamwidth angle and Directivity?
  3. Properties of a driven array.
  4. Relationship between effective length and physical length.
  5. Why we use a earthmat along with antenna?
  6. The power gain of half wave array with respect to a isotropic radiater is?
  7. When loop antenna is radiated through 360 degree, the induced voltage will experience?
  8. The discone antenna can be used as a ?
  9. The number of array in a simplest parasitic array is?
  10. Why we use a counterpoise with the antenna?
  11. Top loading of an antenna may be done by?
  12. The input impedance of a folded dipole antenna is nearly?
  13. Antenna normally preferred for low frequency transmission is?
  14. An antenna behave as resonance circuit when?
  15. What kind of pattern a half wave dipole Produced?
  16. If the height of transmitter and receiver antennas are doubled, what will happen to the range of TV broadcast ?
  17. How the electric field intensity of a Hertzian dipole at a remote point varies as?
  18. What is the common use of loop antenna?
  19. At what frequency a parabolic antenna is commonly used?
  20. What is the radiation pattern of a parabolic antenna?

Click here for the answers of E.C.E  3
Click here for E.C.E 1 Questions
Click here for E.C.E 2 Questions


Answers for E.C.E - 2

Answers of questions of   E.C.E 2

1. BAR, which is further equal to 100 kilopascles.

2. Due to the long term exposure to stress, metal deforms permanently, this phenomenon is          called creeping.
3. Generally,  flux = flow rate / membrane area.
     It is measured by using Ballistic Galvanometer.

4. An ideal volt meter has infinite internal resistance. It acts as a open circuit.
    An ideal am meter has zero internal resistance. It acts as a short circuit.

5. Implantation defects(defects in substrate) causes the leakage current in transistor. It flows through the pn junction when it is inversely polarized.
    Another reason is TiSi gain, which occurs during annealing process.

6. Generally, the slope of load line depends upon Resistor value. 

7. Direct conversion ACD or  Flash ACD 

8. 8