Electronics and Communication Related Interview Questions - 4
61)What is Lenz law ?
An induced current is always in such a direction as to oppose the motion or change causing
it whenever there is an induced electromotive force (emf) in a conductor, it is always in such
a direction that the current it would produce would oppose the change which causes the
induced emf.
If the change is the motion of a conductor through a magnetic field, the induced
current must be in such a direction as to produce a force opposing the motion.
If the change causing the emf is a change of flux threading a coil, the induced current must produce a flux in such a direction as to oppose the change.
62) What is Transmission Frequency of Bluetooth, Wi-Fi and Wi-MAX ?
Bluetooth uses a radio technology called frequency-hopping spread spectrum, which chops
up the data being sent and transmits chunks of it on up to 79 bands (1 MHz each) in the range
2402-2480 MHz.
This range is in the globally unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency band. between 2.402 GHz and 2.480 GHz, to be exact Wi-Fi stands for Wireless Fidelity.
Wi-Fi is based on the IEEE 802.11 family of standards and is primarily a local area networking (LAN) technology designed to provide in-building broadband coverage.
WiMAX is an IP based, wireless broadband access technology that provides performance
similar to 802.11/Wi-Fi networks with the coverage and QOS (quality of service) of cellular
networks. WiMAX is also an acronym meaning "Worldwide Interoperability for Microwave
Access (WiMAX).
WiMAX is a wireless digital communications system, also known as IEEE 802.16, that is
intended for wireless "metropolitan area networks". WiMAX can provide broadband wireless
access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for
mobile stations. In contrast, the WiFi/802.11 wireless local area network standard is limited
in most cases to only 100 - 300 feet (30 - 100m).
63) What is difference between Piconet and Scatternet ?
A piconet is the type of connection that is formed between two or more Bluetooth-enabled
devices, one device takes the role of 'master', and all other devices assume a 'slave' role for
synchronization reasons.
Where as a scatternet is a number of interconnected piconets that supports communication
between more than 8 devices. Scatternets can be formed when a member of one piconet
(either the master or one of the slaves) elects to participate as a slave in a second, separate
piconet.
64) What is Moore's Law ?
The prediction by Gordon Moore (cofounder of the Intel Corporation) that the number of
transistors on a microprocessor would double periodically (approximately every 18 months).
65) How many satellites comprise the GPS and expand it ?
The minimum satellites recquired to track your position is three. That is why it is known as
triangulation. Currently, there are 32 satellites in the GPS system. The exact number varies
as old satellites fail or are retired, and new satellites are sent up to replace them.
66) What is ZigBee and its specifications ?
ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low cost
allows the technology to be widely deployed in wireless control and monitoring applications.
Second, the low power-usage allows longer life with smaller batteries. Third, the mesh
networking provides high reliability and more extensive range. ZigBee relies on the basic
802.15.4 standard to establish radio performance
67) What is FPGA ?
A Field-programmable Gate Array (FPGA) is an integrated circuit designed to be configured
by the customer or designer after manufacturing—hence "field-programmable". Applications
of FPGAs include digital signal processing, software-defined
radio, aerospace and defense systems, ASIC prototyping, medical imaging, computer
vision, speech recognition,cryptography, bioinformatics, computer hardware emulation, radio
astronomy, metal detection and a growing range of other areas.
68) What is MIMO ?
MIMO (multiple input, multiple output) is an antenna technology for wireless
communications in which multiple antennas are used at both the source (transmitter) and the
destination (receiver).
The antennas at each end of the communications circuit are combined
to minimize errors and optimize data speed. MIMO is one of several forms of smart antenna
technology, the others being MISO (multiple input, single output) and SIMO (single input,
multiple output) access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for mobile stations.
In contrast, the WiFi/802.11 wireless local area network standard is limited in most cases to only 100 - 300 feet (30 - 100m).
63) What is difference between Piconet and Scatternet ?
A piconet is the type of connection that is formed between two or more Bluetooth-enabled
devices, one device takes the role of 'master', and all other devices assume a 'slave' role for
synchronization reasons.
Where as a scatternet is a number of interconnected piconets that supports communication
between more than 8 devices. Scatternets can be formed when a member of one piconet
(either the master or one of the slaves) elects to participate as a slave in a second, separate
piconet.
64) What is Moore's Law ?
The prediction by Gordon Moore (cofounder of the Intel Corporation) that the number of
transistors on a microprocessor would double periodically (approximately every 18 months).
65) How many satellites comprise the GPS and expand it ?
The minimum satellites recquired to track your position is three. That is why it is known as
triangulation. Currently, there are 32 satellites in the GPS system. The exact number varies
as old satellites fail or are retired, and new satellites are sent up to replace them.
66) What is ZigBee and its specifications ?
ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low cost
allows the technology to be widely deployed in wireless control and monitoring applications.
Second, the low power-usage allows longer life with smaller batteries. Third, the mesh
networking provides high reliability and more extensive range. ZigBee relies on the basic
802.15.4 standard to establish radio performance
67) What is FPGA ?
A Field-programmable Gate Array (FPGA) is an integrated circuit designed to be configured
by the customer or designer after manufacturing—hence "field-programmable". Applications
of FPGAs include digital signal processing, software-defined
radio, aerospace and defense systems, ASIC prototyping, medical imaging, computer
vision, speech recognition,cryptography, bioinformatics, computer hardware emulation, radio
astronomy, metal detection and a growing range of other areas.
68) What is MIMO ?
MIMO (multiple input, multiple output) is an antenna technology for wireless
communications in which multiple antennas are used at both the source (transmitter) and the
destination (receiver). The antennas at each end of the communications circuit are combined
to minimize errors and optimize data speed. MIMO is one of several forms of smart antenna
technology, the others being MISO (multiple input, single output) and SIMO (single input,
multiple output)
69) What is VOIP ?
VoIP (voice over IP) is an IP telephony term for a set of facilities used to manage the delivery
of voice information over the Internet.VoIP involves sending voice information in digital
form in discrete packets rather than by using the traditional circuit-committed protocols of the
public switched telephone network (PSTN). A major advantage of VoIP and Internet
telephony is that it avoids the tolls charged by ordinary telephone service.
70) On what principle do Transformers work ?
A transformer is a static device that transfers electrical energy from one circuit to another
through inductively coupled conductors—the transformer's coils. A varying current in the
first or primary winding creates a varying magnetic flux in the transformer's core and thus a
varying magnetic field through thesecondary winding. This varying magnetic field induces a
varying electromotive force (EMF) or "voltage" in the secondary winding. This effect is
called mutual induction.
71) What is EDFA ?
Erbium Doped Fiber Amplifier (EDFA) A device that boosts the signal in an optical
fiber. EDFA is an optical repeater device that is used to boost the intensity of optical signals
being carried through a fiber optic communications system. An optical fiber is doped with the
rare earth element erbium so that the glass fiber can absorb light at one frequency and emit
light at another frequency. An external semiconductor laser couples light into the fiber at
infrared wavelengths of either 980 or 1480 nanometers. This action excites the erbium atoms.
Additional optical signals at wavelengths between 1530 and 1620 nanometers enter the fiber
and stimulate the excited erbium atoms to emit photons at the same wavelength as the
incoming signal. This action amplifies a weak optical signal to a higher power, effecting a
boost in the signal strength.
72) What are different types of antennas ?
An antenna (or aerial) is a transducer that transmits or receives electromagnetic waves. In
other words, antennas convert electromagnetic radiation intoelectric current, or vice versa.
They are used to transmit and receive electromagnetic radiation of radio frequency, that
is, radio waves, and are a necessary part of all radio equipment
There are different types of antennas,they can mainly divided into directional & undirectional
a simply type of directional antennas: helical antenna
a simple type of undirectional antennas:yagi & loop antennas
73) What is Yagi-Uda antenna ?
Directional antenna systemconsisting of an array of a dipole and additional closely
coupled parasitic elements (usually a reflector and one or more directors). The dipole in the
array is driven, and another element, typically 5% longer, effectively operates as a reflector.
Other parasitic elements shorter than the dipole may be added in front of the dipole and are
referred to as directors
74) why the input resistance of an op-amp is high whereas it's output resistance is low?
Loading at the input point and to pass the maximum output to the load is the requirement of
Op-Amp which is a current exchange device from input side to output side.
75) what do you understand by microwaves? why these are called micro
Micro waves are those waves whose wavelength is less than a foot(30 cms) or freq ranging
from 1 GHz to 1000 GHz.Because of there tinyness these are called micro.
76) how do microwave oven works??
Heart of microwave oven is magnatron which generates frequency of appox. 2.4 GHz.explain
working of magnatron.
77) What is CMRR? Explain briefly.
CMRR stands for common mode rejection ratio. It is a measure of the ability of a test
instrument to reject
interference that is common to both of its measurement input terminals. It is expressed in
decibels and it is the ratio of the actual or common signal level appearing on the
two input terminals together to the measured level.
78) What is meant by D-FF? D Flip Flop
The D flip-flop is the most common flip-flop in use today. It is better known as delay flip-flop
or data latch.
79) What is the basic difference between Latches and Flip flops?
flip flops are edge-triggered devices whereas latches are level triggered devices.•
latch does not have clock signal whereas flip flop does.•
Flip flop has two values while latch has only one value.•
(Latches do not store information, here, a bit)
80) What is a multiplexer?
A multiplexer, sometimes referred to as a "multiplexor" or simply "mux", is a device that
selects between a number of input signals. In its simplest form, a multiplexer will have two
signal inputs, one control input, and one output.
An everyday example of an analog multiplexer is the source selection control on a home
stereo unit.
Multiplexers are used in building digital semiconductors such as CPUs and graphics
controllers.
In these applications, the number of inputs is generally a multiple of 2 (2, 4, 8, 16, etc.), the
number of outputs is either 1 or relatively small multiple of 2, and the number of control
signals is related to the combined number of inputs and outputs.
An induced current is always in such a direction as to oppose the motion or change causing
it whenever there is an induced electromotive force (emf) in a conductor, it is always in such
a direction that the current it would produce would oppose the change which causes the
induced emf.
If the change is the motion of a conductor through a magnetic field, the induced
current must be in such a direction as to produce a force opposing the motion.
If the change causing the emf is a change of flux threading a coil, the induced current must produce a flux in such a direction as to oppose the change.
62) What is Transmission Frequency of Bluetooth, Wi-Fi and Wi-MAX ?
Bluetooth uses a radio technology called frequency-hopping spread spectrum, which chops
up the data being sent and transmits chunks of it on up to 79 bands (1 MHz each) in the range
2402-2480 MHz.
This range is in the globally unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency band. between 2.402 GHz and 2.480 GHz, to be exact Wi-Fi stands for Wireless Fidelity.
Wi-Fi is based on the IEEE 802.11 family of standards and is primarily a local area networking (LAN) technology designed to provide in-building broadband coverage.
WiMAX is an IP based, wireless broadband access technology that provides performance
similar to 802.11/Wi-Fi networks with the coverage and QOS (quality of service) of cellular
networks. WiMAX is also an acronym meaning "Worldwide Interoperability for Microwave
Access (WiMAX).
WiMAX is a wireless digital communications system, also known as IEEE 802.16, that is
intended for wireless "metropolitan area networks". WiMAX can provide broadband wireless
access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for
mobile stations. In contrast, the WiFi/802.11 wireless local area network standard is limited
in most cases to only 100 - 300 feet (30 - 100m).
63) What is difference between Piconet and Scatternet ?
A piconet is the type of connection that is formed between two or more Bluetooth-enabled
devices, one device takes the role of 'master', and all other devices assume a 'slave' role for
synchronization reasons.
Where as a scatternet is a number of interconnected piconets that supports communication
between more than 8 devices. Scatternets can be formed when a member of one piconet
(either the master or one of the slaves) elects to participate as a slave in a second, separate
piconet.
64) What is Moore's Law ?
The prediction by Gordon Moore (cofounder of the Intel Corporation) that the number of
transistors on a microprocessor would double periodically (approximately every 18 months).
65) How many satellites comprise the GPS and expand it ?
The minimum satellites recquired to track your position is three. That is why it is known as
triangulation. Currently, there are 32 satellites in the GPS system. The exact number varies
as old satellites fail or are retired, and new satellites are sent up to replace them.
66) What is ZigBee and its specifications ?
ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low cost
allows the technology to be widely deployed in wireless control and monitoring applications.
Second, the low power-usage allows longer life with smaller batteries. Third, the mesh
networking provides high reliability and more extensive range. ZigBee relies on the basic
802.15.4 standard to establish radio performance
67) What is FPGA ?
A Field-programmable Gate Array (FPGA) is an integrated circuit designed to be configured
by the customer or designer after manufacturing—hence "field-programmable". Applications
of FPGAs include digital signal processing, software-defined
radio, aerospace and defense systems, ASIC prototyping, medical imaging, computer
vision, speech recognition,cryptography, bioinformatics, computer hardware emulation, radio
astronomy, metal detection and a growing range of other areas.
68) What is MIMO ?
MIMO (multiple input, multiple output) is an antenna technology for wireless
communications in which multiple antennas are used at both the source (transmitter) and the
destination (receiver).
The antennas at each end of the communications circuit are combined
to minimize errors and optimize data speed. MIMO is one of several forms of smart antenna
technology, the others being MISO (multiple input, single output) and SIMO (single input,
multiple output) access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for mobile stations.
In contrast, the WiFi/802.11 wireless local area network standard is limited in most cases to only 100 - 300 feet (30 - 100m).
63) What is difference between Piconet and Scatternet ?
A piconet is the type of connection that is formed between two or more Bluetooth-enabled
devices, one device takes the role of 'master', and all other devices assume a 'slave' role for
synchronization reasons.
Where as a scatternet is a number of interconnected piconets that supports communication
between more than 8 devices. Scatternets can be formed when a member of one piconet
(either the master or one of the slaves) elects to participate as a slave in a second, separate
piconet.
64) What is Moore's Law ?
The prediction by Gordon Moore (cofounder of the Intel Corporation) that the number of
transistors on a microprocessor would double periodically (approximately every 18 months).
65) How many satellites comprise the GPS and expand it ?
The minimum satellites recquired to track your position is three. That is why it is known as
triangulation. Currently, there are 32 satellites in the GPS system. The exact number varies
as old satellites fail or are retired, and new satellites are sent up to replace them.
66) What is ZigBee and its specifications ?
ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low cost
allows the technology to be widely deployed in wireless control and monitoring applications.
Second, the low power-usage allows longer life with smaller batteries. Third, the mesh
networking provides high reliability and more extensive range. ZigBee relies on the basic
802.15.4 standard to establish radio performance
67) What is FPGA ?
A Field-programmable Gate Array (FPGA) is an integrated circuit designed to be configured
by the customer or designer after manufacturing—hence "field-programmable". Applications
of FPGAs include digital signal processing, software-defined
radio, aerospace and defense systems, ASIC prototyping, medical imaging, computer
vision, speech recognition,cryptography, bioinformatics, computer hardware emulation, radio
astronomy, metal detection and a growing range of other areas.
68) What is MIMO ?
MIMO (multiple input, multiple output) is an antenna technology for wireless
communications in which multiple antennas are used at both the source (transmitter) and the
destination (receiver). The antennas at each end of the communications circuit are combined
to minimize errors and optimize data speed. MIMO is one of several forms of smart antenna
technology, the others being MISO (multiple input, single output) and SIMO (single input,
multiple output)
69) What is VOIP ?
VoIP (voice over IP) is an IP telephony term for a set of facilities used to manage the delivery
of voice information over the Internet.VoIP involves sending voice information in digital
form in discrete packets rather than by using the traditional circuit-committed protocols of the
public switched telephone network (PSTN). A major advantage of VoIP and Internet
telephony is that it avoids the tolls charged by ordinary telephone service.
70) On what principle do Transformers work ?
A transformer is a static device that transfers electrical energy from one circuit to another
through inductively coupled conductors—the transformer's coils. A varying current in the
first or primary winding creates a varying magnetic flux in the transformer's core and thus a
varying magnetic field through thesecondary winding. This varying magnetic field induces a
varying electromotive force (EMF) or "voltage" in the secondary winding. This effect is
called mutual induction.
71) What is EDFA ?
Erbium Doped Fiber Amplifier (EDFA) A device that boosts the signal in an optical
fiber. EDFA is an optical repeater device that is used to boost the intensity of optical signals
being carried through a fiber optic communications system. An optical fiber is doped with the
rare earth element erbium so that the glass fiber can absorb light at one frequency and emit
light at another frequency. An external semiconductor laser couples light into the fiber at
infrared wavelengths of either 980 or 1480 nanometers. This action excites the erbium atoms.
Additional optical signals at wavelengths between 1530 and 1620 nanometers enter the fiber
and stimulate the excited erbium atoms to emit photons at the same wavelength as the
incoming signal. This action amplifies a weak optical signal to a higher power, effecting a
boost in the signal strength.
72) What are different types of antennas ?
An antenna (or aerial) is a transducer that transmits or receives electromagnetic waves. In
other words, antennas convert electromagnetic radiation intoelectric current, or vice versa.
They are used to transmit and receive electromagnetic radiation of radio frequency, that
is, radio waves, and are a necessary part of all radio equipment
There are different types of antennas,they can mainly divided into directional & undirectional
a simply type of directional antennas: helical antenna
a simple type of undirectional antennas:yagi & loop antennas
73) What is Yagi-Uda antenna ?
Directional antenna systemconsisting of an array of a dipole and additional closely
coupled parasitic elements (usually a reflector and one or more directors). The dipole in the
array is driven, and another element, typically 5% longer, effectively operates as a reflector.
Other parasitic elements shorter than the dipole may be added in front of the dipole and are
referred to as directors
74) why the input resistance of an op-amp is high whereas it's output resistance is low?
Loading at the input point and to pass the maximum output to the load is the requirement of
Op-Amp which is a current exchange device from input side to output side.
75) what do you understand by microwaves? why these are called micro
Micro waves are those waves whose wavelength is less than a foot(30 cms) or freq ranging
from 1 GHz to 1000 GHz.Because of there tinyness these are called micro.
76) how do microwave oven works??
Heart of microwave oven is magnatron which generates frequency of appox. 2.4 GHz.explain
working of magnatron.
77) What is CMRR? Explain briefly.
CMRR stands for common mode rejection ratio. It is a measure of the ability of a test
instrument to reject
interference that is common to both of its measurement input terminals. It is expressed in
decibels and it is the ratio of the actual or common signal level appearing on the
two input terminals together to the measured level.
78) What is meant by D-FF? D Flip Flop
The D flip-flop is the most common flip-flop in use today. It is better known as delay flip-flop
or data latch.
79) What is the basic difference between Latches and Flip flops?
flip flops are edge-triggered devices whereas latches are level triggered devices.•
latch does not have clock signal whereas flip flop does.•
Flip flop has two values while latch has only one value.•
(Latches do not store information, here, a bit)
80) What is a multiplexer?
A multiplexer, sometimes referred to as a "multiplexor" or simply "mux", is a device that
selects between a number of input signals. In its simplest form, a multiplexer will have two
signal inputs, one control input, and one output.
An everyday example of an analog multiplexer is the source selection control on a home
stereo unit.
Multiplexers are used in building digital semiconductors such as CPUs and graphics
controllers.
In these applications, the number of inputs is generally a multiple of 2 (2, 4, 8, 16, etc.), the
number of outputs is either 1 or relatively small multiple of 2, and the number of control
signals is related to the combined number of inputs and outputs.
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