Top 100 Best Interview Questions and Answers for Electronics & Communication.

In this tutorial, we are going to learn about Best Interview Questions and Answers for Electronics & Communication.

Q1.What is Electronics?

Answer. The use of electrical devices which operate by controlling the flow of electrons or other electrically charged particles. We are using many types of electronics devices in home appliance like mobile, laptop, LED T.V. and other DC operated device called electronics devices.

Q2.What is the difference between electronics and electrical?

Answer. Electronics work on dc and with a voltage range of -48vDC to +48vDC of the electronic devices is plugged into a standard wall outlet, there will be a transformer inside which will convert the AC voltage you are supplying to the required DC voltage needed by the device. Examples: Computer, radio, T.V. etc..

Electric devices use line voltage (120vAC, 240vAV,etc…). Electric devoices can also be designed to operate on DC sources, but will be at DC voltages above 48v. Examples are incandescent lights, heaters, fridge, stove, etc …

Q3.What is communication?

Answer .Communication means transferring a signal from the transmitter which passes as transferring of message from one place to another place called communication. All types of mobile and telephone related equipments are communicating devices.

Q4.How many types of communications?

Answer. Mainly two types of communication like Analog and Digital communication.

Analog communication, analog is the process of taking an audio or video signal (the human voice) and translating it into electronic pulses. Digital on the other hand is braking the signal into a binary format where the audio or video data is represented by a series of “1”s and “0”s.

Digital signals are immune to noise, quality of transmission and reception is good, components used in digital communication can be proceed with high perception and power consumption is also very less when compared with  analog signals.

Q5. What is latch up?

Answer: Latch-up pertains to a failure mechanism wherein a parasitic thyristor (such as a parasitic silicon controlled rectifier, or SCR) is inadvertently created within a circuit, causing a high amount of current to continuously flow through it once it is accidently triggered or turned on. Depending on the circuits involved, the amount of current flow produced by this mechanism can be large enough to result in permanent destruction of the device due to electrical overstress (EOS).

Q6. What is diode?

Answer: In electronics, a diode is a two terminal device. Diodes have two active electrodes between which the signal of interest may flow, and most are used for their unidirectional current property & diode have many types in electronics which are using dependant on application. Diode like – ZENER diode, General Purpose diode, Schottky diode & high power diode etc.

Q7. What is transistor?

Answer: In electronics, a transistor is a semiconductor device commonly used to amplify or switch to electronic signals. The transistor is the fundamental building block of computers, and all other modern electronic devices. Some transistors are packaged individually but most are found in integrated circuits, Basically two types of transistor in electronics application like NPN & PNP which are working on forward bias and reverse bias.

Q8. What is sampling?

Answer: The process of obtaining a set of samples from a continuous function of time x(t) is referred to as sampling.

Q9. What is State sampling theorem?

Answer: It states that, while taking the samples of a continuous signal, it has to be taken care that the sampling rate is equal to or greater than twice the cut off frequency and the minimum sampling rate is known as Nyquist rate.

Q10. What are the advantages of resistors?

Answer – Resistance is most important components of electronics circuit which are use to oppose the flow of current and below are the advantage of resistance

1. Resistors are very small in size.

2. It is very easy to carry resistors from one place to another place.

3. Resistors are very cheap.

Q11. What is the principle of microwave?

Answer: Microwave essentially means very short wave. The microwave frequency spectrum is usually taken to extend from 1GHZ to 30GHZ. The main reasons why we have to go in microwave frequency band are congested and demand for point to point communication continues to increase. The propagation of the microwave takes place in space wave in v

Q12. What is cut off frequency?

Answer: the frequency at which the response is -3dB with respect to the maximum response.

Q13. What is pass band?

Answer: The Pass band is the range of frequencies or wavelengths that can pass through a filter without being attenuated.

Q14. What is stop band?

Answer. a stop band is a band of frequencies, between specified limits, in which a circuit, does not let signals through, or the attenuation is above the required stop band attenuation level.

Q15. What is Power rating?

Answer. The power rating of a diode is defined as the maximum value of power that can be dissipated without failure if V f is the forward biased voltage and if is the forward biased current .

Q16. What is rheostat?

Answer: Rheostat is a type of variable resistor which is used to control the flow of electric current by manually increasing or decreasing its resistance.

Q17. What is demodulation?

Answer: Demodulation is the act of removing the modulation from an analog signal to get the original baseband signal back. Demodulating is necessary because the receiver system receives a modulated signal with specific characteristics and it needs to turn it to base-band.

Q18. What is radio environment in building?

Answer:

1. Building penetration: Building penetration depends on the material used for construction and architecture used. This varies building to building and is based on building construction.

2. Building height effect: The signal strength is always higher at top floor and generally floor gain height is about 2.7dB/floor which not dependent on building construction.

3. Building floor reception: The signal isolation between floors in a multi color building is on the average about 20dB. Within a floor of 150*150 feet, the propagation loss due to interior walls, depending on the wall materials is about 20dB between the strong and the weak areas.

Q19. What is resistor?

Answer: A resistor is a two-terminal electronic component that opposes an electric current by producing a voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm’s law:

V=IR

Q20. What is inductor?

Answer: An inductor is a passive electric device employed in electrical circuits or its property of inductance. An inductor can take many forms& Inductors are many types like  Air-core Inductor, Iron-Core Inductor, Toroidal Inductors, Laminated Core Inductors & Powdered Iron Core Inductors.

Q20.What is conductor?

Answer: A substance, body, or device that readily conducts heat, electricity, sound, etc. Copper is a good conductor of electricity & there are many types of conductor like Hard Drawn Copper Conductor, Cadmium Copper Conductor, Steel-Cored Copper Conductor (SCC) , Copper Welded Conductor, Hard-Drawn Aluminum Conductor or All Aluminum Conductor., Aluminum Conductor Steel Reinforced & Smooth Body ACSR Conductor.

Q21. What is a semi conductor?

Answer: A semiconductor is a solid material that has electricity conductivity in between that of  a conductor and that of an insulator (An insulator is a material that resists the flow of electric current) . it is an object intended to support or separate electric conductors without passing current through itself); it can vary over that wide range either permanently or dynamically.

Q22. Name the modulation techniques?

Ans. For analog modulation– AM,SSB,FM,PM and SM.

Digital modulation–OOK,FSK,Psk, QAM,MSK,CPM,PPM.TCM,OFDM.

Q23. What is  AM and FM?

AM-Amplitude modulation is a type of modulation where the amplitude of carried signal is varied in accordance with the information bearing signal.

FM-Frequency modulation is a type of modulation where the frequency of the carrier signal is varied in accordance with the information bearing signal.

Q24. What is RF?

Answer: Radio frequency is a frequency or rate of oscillation within the range of about 3 HZ to 300 GHZ. this range corresponds to frequency of alternating current electrical signals used to produced and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electric circuits or electromagnetic radiations.

Q25. What is the modulation? And where it is utilized?

Answer: Modulation is the process of varying some characteristic of a period wave with an external signals.Radio communication superimposes this information bearing signal onto a carrier signal. these high frequency carrier signals can be transmitted over the air easily and are capable of travelling long distances. The characteristics (amplitude, frequency or phase) of the carrier signal are varied in accordance with the information bearing signal.

Modulation is utilized to send an information bearing signal over long distances.

Q26. Where do we use AM and FM?

Answer: AM is used for video signals for example TV. Ranges from 535 to 1705 kHz. FM is used for audio signals for example Radio. Ranges from 88 to 108 MHz.

Q27. What is a base station?

Answer: Base station is a radio receiver /transmitter that serves as the hub of the local wireless network, and, may also be the gateway between a wired network and the wireless network.

Q28. What are the parts of network management system (NMS)?

Answer: Following are the parts of Network management system :

1. OMC: Operations and maintenance centre – Computerized monitoring center.

2. NMC: Network Management center- Centralized control of a network is done here.

3. OSS: Operation and support system – Used for supporting activities performed in an OMC and/ or NMC.

Q29. How many satellites are required to cover the earth?

Answer: 3 satellites are required to cover the entire earth, which is placed at 120 degree to each other. the life span of the satellite is about 15 years.

Q30. What are GPRS services?

Answer: GPRS services are defined to fall in one of the two categories:

1.PTP(Point to Point)

2.PTM(Point to Multi point)

Some of the GPRS services are not likely to be provided by network operations during early deployment of GPRS is due in part of the phased development of standard. Market demand is another factor affecting the decision of operators regarding which services to offer first.

Q30. What is a repeater?

Answer: A repeater is an electric device that receives a signal and retransmits it at a higher level and/or higher power or onto the other side of an obstruction, so that the signal can cover longer distance without degradation.

Q31. What is an amplifier?

Answer: An electronic device or electrical circuit which is used to boost (amplify) the power, voltage or current of an applied signal.

Q32. Example for negative feedback and positive feedback?

Answer: Examples for negative feedback is –Amplifiers and for +ve feedback is Oscillators.

Q33.How can a pseudorandom noise code be usable?

Answer: To be usable for direct sequence spreading. a PN code must meet the following conditions:

1. Sequence must be built from two leveled numbers.

2. The code must have to correlation peak to enable code synchronization. 

3. Code must have a low cost correlation value, the lower it is more than number of users which can be allowed in the system.

4. The codes should be “balanced” i.e. the difference between ones and zeroes in could may only be one.

Q34. What is Oscillator?

Answer: An oscillator is a circuit that creates a waveform output from a direct current input. The two main types of oscillator are harmonic and relaxation. The harmonic oscillators have smooth curved waveforms, while relaxation oscillators have waveform with sharp changes.

Q35 what is an integrated circuit?

Answer: An integrated circuit (IC) , also called a microchip, is an electronic circuit etched onto a silicon chip. Their main advantages are low cost, low power, high performance and very small size.

Q36 what is handover and what are its types?

Answer: Handover in mobile communication refers to the process of transferring a call from one network cell to another without breaking the call. There are two types of handover which are as follows:

1. Hard Handoff: hard handoff is the process in which the cell connection is disconnected from the previous cell before it is made with the new one.

2. Soft Handoff: it is the process in which a new connection is established first before disconnecting the old one. It is thus more efficient and smart.

Q37. What is op-amp?

Answer: An operational amplifier often called an op-amp is a DC- coupled high gain electronic voltage amplifier with differential inputs and, usually, a single output. Typically the output of the op-amp is controlled either by negative feedback, which largely determines the magnitude of its output voltage gain, or by positive feedback which facilitates regenerative gain and oscillation.

Q38. What is Bluetooth?

Answer: Bluetooth is designed to be a personal area network, where participating entities are mobile and require sporadic communication with others. it is Omni directional i.e. it does not have line of sight limitation like infra red does. Ericson started the work on Bluetooth and named it after the Danish king Harold Bluetooth. Bluetooth operates in the 2.4 ghz area of spectrum and provides range of 10 meters. it offers transfer speeds.

Q39.What is a feedback?

Answer: Feedback is a process whereby some proportion of the output signal of a system is passed (fed back) to the input. This is often used to control the dynamic behavior of the system.

Q40. What are CDMA, TDMA, and FDMA?

Answer: Code Davison Multiple Access is a channel access method utilized by various radio communication technologies. CDMA employs spread spectrum technology and a special coding scheme (where each transmitter assigned to code) to allow multiple users to be multiplexed over the same physical channel. By contrast time division multiple access (TDMA) divides access by time, while frequency division multiple access divides it by frequency.

An analogy to the problem of multiple accesses is a room (channel) in which people wish it communicate with each other. to avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division) or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same languages can understand each other, but not other people. Similarly in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.

Q42. Explain different types of feedback

Answer: Types of feedback:

Negative feedback: this tends to reduce output (but in amplifiers, stabilizes and liveries operation). Negative feedback feeds part of a system’s output, inverted into the systems input; generally with the result that fluctuations are attenuated.

Positive feedback: this tends to increase output. Positive feedback, sometimes referred to as “mutative causation”, is a feedback loop system in which the system responds to perturbation (A perturbation means a system, is an alteration of function, induced by external and internal mechanism) in the same direction as the perturbation. In contrast a system that responds to the perturbation in the opposite direction is called a negative feedback system.

Bipolar feedback: which can either increase or decrease output.

Q43. What is communication?

Answer. Communication denotes exchange of information, where a message is sent and received. It can be either half duplex. Full duplex and simplex.

Q44. What is channel with respect to communication?

Answer. It is to transmit and receive information, path is required. This path is called communication channel. it can be either a cable (fiber, optic, twisted pair etc.) or can be broadcast (satellite, radio etc..)

Q45. What is half duplex?

Answer. we use a single path for communication. Since we use only one path we can either transmit or receive at a time but not at the same time. Example one way traffic, walkie-talkie.

Q46. What is full duplex?

Answer. Full duplex means information can be sent and received in both the directions (from sender side and receiver side) at the same time. example: high way road – on both sides vehicle can move at the same time.

Q47. What is simplex communication system?

Answer. In simplex communication system, we either transmit or receive but we cannot do both at same time. For example in broadcast system only one transmitter is used to transmit information but one or many receivers will be used to receive it (news headlines scrolling in tv).

Q48. What is serial and parallel communication?

Answer. Data can be transmitted between a sender and a receiver in two main ways:

1. Serial

2. Parallel

3. Serial communication is the method of translating one bit at a time through a medium.

   For example: Ethernet, RS-232, USB etc

4. Parallel communication is the method of transferring blocks. For example a BYTE of data is transmitted at the same time.

For example: Computer peripheral buses like: ISA, ATA, SCSI, PCI, RAM etc.

 Q49.What is modulation?

Answer. Modulation is a technique to transmit a signal over a long distance by varying properties of a waveform in a carrier signal.

Q50. What is coding?

Answer. Messages are transmitted and received as bits. Based on the different applications we make the bits to fit into it accordingly. There are four different types of coding. They are types of like that:

a. Data compression

b. Error correction

c. Cryptographic coding

d. Line coding

Q51. Why antenna is required?

Answer. Transmission and reception of signals in proper frequency can be done by the antennas. This transmission and reception of signals can be single direction or multiple directions. This depends upon the directivity of the antenna. The length of the antenna is decided by the frequency of transmission or reception.

Q52. What is base station?

Answer. it simple works it is like host computer access details are maintained. Base station is where many antennas will be placed so that many users get connected to it.

Q53. How many types of electrical components?

Answer: 1. Active components & 2. Passive components

Passive components-

 a. Passive components are devices which stores energy in the form of voltage or current.

 b. The components which cannot control the flow of current.

c. Passive components cannot provide any power gain to the circuit.

d. For example: Resistors, Capacitors, Inductors, and Transformers

2) Active components –

 a. Active components generate energy in the form of voltage or current.

b. They supply energy to the circuit and they cannot control the flow of current.

c. They can provide power gain to the circuit.

d. For example:  Transistors, Triode, Vacuum tubes, and Voltage sources.

Q54.What is Circuit & Types?

Answer-

1. Circuit can be electrical, electronic, analog, digital, synchronous, asynchronous etc.

2. Electrical circuit- A complete electrical network with a closed loop giving a return path for current.

3. Electronic circuit- it is a combination of electronic components capable of performing amplification, computation and data transfer.

4. Analog circuit uses continues and digital circuit uses discrete signal levels respectively.

Q55. What is series circuit?

Answer-

1. Components are wired one after another.

2. Electricity will pass through first component, then the next component, then the next, and so on.

3. In a series circuit, the current through each of the components is the same, and the voltage across is the sum of the voltages across each component.

Q56. What is Parallel Circuit?

Answer-

1. Components are wired side by side.

2. Electricity passes through all of them at the same time, from one common point to another common point.

3. In a parallel circuit, the voltage across each of the components is the same, and the total current is the sum of the currents through each component.

Q57. What is Closed Circuit?

Answer-

1. A complete electrical circuit through which current can flow when a voltage is applied.

2. A closed circuit will allow the flow of electricity between power and ground.

3. It is used when requiring the use of current.

Q58. What is Open Circuit?

Answer:

1. An incomplete electrical circuit in which no current flows.

2. An open circuit will break the flow of electricity between power and ground.

Q59. What is Current?

Answer:

1. Current is the movement or flow of electric charge.

2. Or continuous and uniform flow of charge around the circuit.

3. According to ohm’s law, current is given by I=VIR

4. Measured in units of ‘Amperes’.

Q60. What is Alternating Current (AC)?

Answer:

1. In AC the direction of electricity flowing throughout the circuit is constantly reversing.

2. AC is obtained from alternator.

3. It can be transmitted over long distance with some losses.

4. For Example: Current flowing in power lines or normal household electricity that comes from a wall outlet.

Q61. What is Direct Current (DC)?

1. In DC the flow of electric charge is unidirectional.

2. DC is obtained from Generators, battery, solar cell, etc.

3. It can be transmitted over very long distance with negligible losses.

4. Used to charge batteries, Cell phones, Flat screen TVs

(AC goes into the TV, which is converted to DC), Flashlights etc.

Q62. What is Voltage (V)?

Answer:

1. Voltage is the difference in electric potential between two points.

2. According to Ohm’s law, Voltage is given by

V=I*R

3. Measured in units of ‘volts’.

Q63. What are applications of buffer?

Answer.

         a. they are used to introduce small delays.

         b. they are used to eliminate cross talk caused due to closs routing.

         c. they are used to support high fan-out.

Q64. Give two ways of converting a two input NAND gate to an inverter?

Answer:

        a. short the 2 inputs of the NAND gate and apply the single input to it.

         b. connect the output to one of the input and the other to the input signal.

Q70. Why is most interrupts active low?

Answer. if you consider the transistor level of a module, active low means the capacitor in the output terminal gets charged or discharged based on low to high to low transition respectively.

Q71. What is Difference between D(Data) -Latch and D(Data) flip-flop?

Answer. D-latch is level sensitive where as flip-flop is edge sensitive. Flip-flops are made up of latches.

Q72. What is multiplexer?

Answer. It is a combinational circuit that selects binary information from one of many input lines and directs it to a signal output line. Where ‘n’ is selection line.

Q73. What is transducer?

Answer. A Converts a physical variable to an electrical variable.

Q74. Describe offset error for a DAC (Digital Analog Convertor)?

Answer. More or less input voltage is required for the first step than what is specified.

Q75. What is the conversion time of a flash convertor?

Answer. The conversion takes place continuously.

Q76. What is the major advantage of the R/2R ladder DAC as compared to a binary-weighted-input DAC (digital analog convertor)?

Answer. It is uses only two different resistor values.

Q77. What is the accuracy of a D/A (digital/analog) convertor?

Answer. it is the comparison between the actual output of the convertor and its expected output.

Q78.What is the difference between PLA (Programmable Logic Array) and PAL (Programmable Logic Array) and PAL (Programmable Array Logic)?

Answer. The PLA has a programmable OR plane and a programmable AND plane, while the PAL only has a programmable AND plane.

Q79. What is the difference between microprocessor/ DSP (digital signal processor) systems and other digital systems?

Answer. The digital system follows a programmed sequence of infrastructions that the designer specified.

Q80. The process of designing a synchronous counter that will count in a non binary manner is primarily based on?

Answer. External logic circuits that decode the various states of the counter to apply the correct logic levels to the J-K inputs.

Q81. Which of the following statements does NOT describe an advantage of digital technology?

Answer. The values may vary over a continuous range.

Q82. What does parallel transmission of digital data requires?

Answer. the parallel transmission requires as many signal lines between sender and receiver as these are data bits.

Q83. What is one relative disadvantage of serial transfer?

Answer. It is slow

Q84. Latches constructed with NOR and NAND gates tend to remain in the latched condition due to which configuration feature?

Answer. Cross Coupling

Q85. When is a flip-flop said to be transparent?

Answer. When the Q output follows the input

Q86. In VHDL (VHSIC Hardware Description Language). how is each instance of a component addressed?

Answer. A name followed by a colon and the name of the library primitive.

Q87. Give only two x-or gates one must function as buffer and another as inverter?

Answer.

        a. Tie one of x-or gates input to 1 it will act as inverter.

         b. Tie one of x-or gates input to 0 it will act as buffer.

Q88. How to achieve 180 degree exact phase shift?

Answer.

             a. Never tell using inverter.

              b. DCM (Digital Content Management) an inbuilt resource in most of FPG(Field –       Programmable Gate Array) can be configured to get 180 degree phase shift.

Q89. What is significance of RAS and CAS in SDRAM?

Answer. SDRAM (Synchronous dynamic random access memory ) receives its address command in two address words. it uses a multiple scheme to save input pins.

B. the first address ward is latched into the DRAM (dynamic random access memory) chip with the Row Address strobe (RAS).

C. Shortly after the RAS and CAS (Central Authentication Service) strobes, the stored data is valid for reading.

Q90. How can you convert an SR Flip-flop to a JK Flip-flop?

Answer. By giving the feedback we can convert, Q=>S and Q=>R. Hence the S and R inputs will act as J and K respectively.

Q91. In a bit Johnson’s counter what are the unused states?

Answer. a. 2 (power n)-2n (Number) is the one used to find the unused states in Johnson counter.

          b. So for a 3-bit counter it is 8-6=2. Unused states=2. The two unused states are 010 and 101.

Q92. What is difference between RAM (Random-access memory) and FIFO (First in first out)?

Answer. FIFO does not have address lines RAM is used for storage purpose where as FIFO is used for synchronization purpose. When two peripherals are working in different clock domains then we will go for FIFO.

Q93. What is embedded?

Answer. It is an arrangement in which all its units, assembled work together according to set of rules, Example – watch is a time displaying system.

Q94. What is embedded System?

Answer.  It is a combination of software & hardware. It is designed to perform a particular task, the task has to be completed in a given time, Example – Mobile phone, washing machine & microwave etc.

Q95. What is microprocessor?

Answer.

  • An integrated computer circuit which perform all the function of a CPU (central processing unit).
  • A semiconductor device (integrated circuit) manufactured by using the LSI (large – scale integration) technique.
  • It includes the ALU (Arithmetic Logic Unit), register arrays, and control circuits on a single chip.

Q96. What is micro-computer?

Answer. A computer that is designed using a microprocessor as its CPU (central processing unit), it includes microprocessor, memory and I/O (input / output).

Q97. What is ROM (Read – Only memory)?

Answer – A memory that stores binary information permanently. The information can be read from this memory but cannot altered.

Q98. What is microcontroller?

Answer – A device that includes microprocessor, memory and I/O (Input / Output) signal lines on a signal chip, fabricated using VLSI (very – large – scale – integration).

Q99. What is Assembler?

Answer. A computer program that translate an assembly language program from memories to the binary machine code of a computer.

Q100. What is Flag?

Answer. The data conditions, after arithmetic or logical operations, are indicated by setting or resetting the filp-flop called Flag.

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