22329 Applied Electronics Viva Questions with Answers
Q1. What is
Electronics?
Ans: The study and
use of electrical devices that operate by controlling the flow of electrons or
other electrically charged particles.
Q2. What is the
difference between Electronics and Electrical?
Ans: Electronics
work on DC and with a voltage range of -48vDC to +48vDC. If the electronic
device 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, 240vAC, etc...). Electric devices 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?
Ans: Communication
means transferring a signal from the transmitter which passes through a medium
then the output is obtained at the receiver. (or)communication says as
transferring of message from one place to another place called communication.
Q4. Different
types of communications? Explain.
Ans: Analog and
digital communication.
As a technology,
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 breaking
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 produced with high precision and power
consumption is also very less when compared with analog signals.
Q5. What is latch
up?
Ans: 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 accidentally 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?
Ans: 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.
Q7. What is
transistor?
Ans: In electronics,
a transistor is a semiconductor device commonly used to amplify or switch
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
Q8. What is
sampling?
Ans: The process of
obtaining a set of samples from a continuous function of time x(t) is referred
to as sampling.
Q9. State
sampling theorem.
Ans: 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 the Nyquist rate.
Q10. What are the
advantages of resistors?
Ans:
- Resistors are very small in size.
- It is very easy to carry resistors from one place to another place.
- Resistors are very cheap.
Q12. What is
cut-off frequency?
Ans: The frequency
at which the response is -3dB with respect to the maximum response.
Q13. What is pass
band?
Ans: Passband is the
range of frequencies or wavelengths that can pass through a filter without
being attenuated.
Q14. What is stop
band?
Ans: A stopband is a band of frequencies, between specified limits, in which a circuit, such as a filter or telephone circuit, does not let signals through, or the attenuation is above the required stopband attenuation level.
Q15. Define Power
Rating?
Ans: 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 I f is the
forward biased current.
Pd= V f x I f.
Q16. What is
rheostat.
Ans: Rheostat is a type of variable resistor which is used to control the flow of electric current by manually increasing or decreasing its resistance.
Q16. What is
demodulation?
Ans: 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.
Q17. Explain
radio environment in building.
Ans:
- 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.
- Building Height Effect: The signal strength is always higher at top
floor and generally floor gain height is about 2.7dB/floor which is not
dependent on building construction.
- Building Floor Reception: The signal isolation between floors in a multi floor 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 20 dB between the strong and the weak areas.
Q18. What is
resistor?
Ans: 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.
Q19. What is
inductor?
Ans: An inductor is
a passive electrical device employed in electrical circuits for its property of
inductance. An inductor can take many forms.
Q20. What is
conductor?
Ans: A substance,
body, or device that readily conducts heat, electricity, sound, etc. Copper is
a good conductor of electricity.
Q21. What is a
semi conductor?
Ans: A semiconductor
is a solid material that has electrical 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 electrical
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, ASK, Psk, QAM, MSK, CPM, PPM, TCM, OFDM
Q23. Explain AM
and FM.
AM-Amplitude modulation is a type of modulation where the amplitude of
the carrier 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. Explain RF?
Ans: Radio frequency (RF) 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 produce 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 electrical circuits or electromagnetic radiation.
Q25. What is
modulation? And where it is utilized?
Ans: Modulation is
the process of varying some characteristic of a periodic 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?
Ans: 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?
Ans: 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)?
Ans: Following are
the parts of network management system:
- OMC: Operation and maintenance center – Computerized monitoring
center.
- NMC: Network Management Center – Centralized control of a network
is done here.
- 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?
Ans: 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.
Q29. What are
GPRS services?
Ans: GPRS services
are defined to fall in one of the two categories:
- PTP (Point to point)
- PTM (Point to Multi point)
Some of the GPRS services are not likely to be provided by network operators during early deployment of GPRS due in part to 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?
Ans: A repeater is
an electronic 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 distances without degradation.
Q31. What is an
Amplifier?
Ans: An electronic
device or electrical circuit that is used to boost (amplify) the power, voltage
or current of an applied signal.
Q32. Example for
negative feedback and positive feedback?
Ans: Example for ve
feedback is ---Amplifiers And for +ve feedback is Oscillators
Q33. How can a
Pseudo Random Noise Code be usable?
Ans: To be usable
for direct sequence spreading, a PN code must meet the following conditions:
- Sequence must be built from 2 leveled numbers.
- The codes must have sharp auto correlation peak to enable code
synchronization.
- Codes must have a low cross-correlation value, the lower it is,
more are the number of users which can be allowed in the system.
- The codes should be “balanced” i.e. the difference between ones and
zeros in code may only be one.
Q34. What is
Oscillator?
Ans: 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 waveforms with sharp changes.
Q35. What is an
Integrated Circuit?
Ans: 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?
Ans: 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
crosstalk?
Ans: Crosstalk is a form of interference caused by signals in nearby conductors. The most common example is hearing an unwanted conversation on the telephone. Crosstalk can also occur in radios, televisions, networking equipment, and even electric guitars.
Q38. What is
op-amp?
Ans: An operational
amplifier, often called an op-amp , is a DC-coupled high-gain electronic
voltage amplifier with differential inputs[1] 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.
Q39. Explain
Bluetooth.
Ans: 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. Ericsson 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 a range of 10 meters. It offers transfer speeds of around 720 Kbps.
Q40. What is a
feedback?
Ans: 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 behaviour of the
system.
Q41. What is
CDMA, TDMA, FDMA?
Ans: Code division
multiple access (CDMA) is a channel access method utilized by various radio
communication technologies. CDMA employs spread-spectrum technology and a
special coding scheme (where each transmitter is assigned a 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 (FDMA) divides it by frequency.
An analogy to the
problem of multiple access is a room (channel) in which people wish to
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 language 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
Ans: Types of
feedback:
Negative feedback:
This tends to reduce output (but in amplifiers, stabilizes and linearizes
operation). Negative feedback feeds part of a system's output, inverted, into
the system's input; generally with the result that fluctuations are attenuated.
Positive feedback:
This tends to increase output. Positive feedback, sometimes referred to as
"cumulative 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 or internal mechanisms) 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 are the
main divisions of power system?
Ans: The generating
system,transmission system,and distribution system
Q44. What is
Instrumentation Amplifier (IA) and what are all the advantages?
Ans: An
instrumentation amplifier is a differential op-amp circuit providing high input
impedances with ease of gain adjustment by varying a single resistor.
Q45. Explain the
concept of frequency re-use.
Ans: The whole of
the geographical area is divided into hexagonal shape geometrical area called
cell and each cell having its own transceiver. Each BTS (cell site) allocated
different band of frequency or different channel. Each BTS antenna is designed
in such a way that i cover cell area in which it is placed with frequency
allotted without interfering other sell signal.