100525 + Interview Questions in GENERAL QA IN GENERAL AWARENESS Page 532 InterviewSolution

26551.

In commercial TV transmission in India, picture and speech signals are modulated respectively(Picture)(Speech)(a)VSBVSB(b)VSBSSB(c)VSBFM(d)FMVSB

Answer»

	(Picture	h signals are modulated respectively (Picture) (
(c)	VSB	FM

Note that VSB modulation is the clever compromise between SSB and DSB. Since TV bandwidth is large so VSB is used for picture transmission. Also, FM is the best option for speech because of better noise immunity

Discussion

26552.	A 4 GHz carrier is DSB-SC modulated by a low-pass message signal with maximum frequency of 2 MHz. The resultant signal is to be ideally sampled. The minimum frequency of the sampling impulse train should be (a) 4 MHz (b) 8 MHz (c) 8 GHz (d) 8.004 GHz
Answer» (b) 8 MHz Given fc = 4GHz and fm = 2 MHz Such a signal is amplitude modulated (DSB-SC) i.e. two side bands = fc +fm and fc – fm = 4002 and 3998 ; BW = 4 MHz so, min. sampling frequency should be (Nyquist Rate) = 2 *4 MHz = 8MHz

26552.

A 4 GHz carrier is DSB-SC modulated by a low-pass message signal with maximum frequency of 2 MHz. The resultant signal is to be ideally sampled. The minimum frequency of the sampling impulse train should be (a) 4 MHz (b) 8 MHz (c) 8 GHz (d) 8.004 GHz

Answer»

(b) 8 MHz

Given fc = 4GHz and fm = 2 MHz

Such a signal is amplitude modulated (DSB-SC) i.e. two side bands = fc +fm and fc – fm

= 4002 and 3998 ; BW = 4 MHz

so, min. sampling frequency should be (Nyquist Rate) = 2 *4 MHz = 8MHz

Discussion

26553.	In FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of A. mf B. 3mf C. mf/3 D. mf/9
Answer» B. 3mf Frequency multiplier increase the deviation, β = Δf/fm If multiplied by three,3 β = 3Δf/fm

26553.

In FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of A. mf B. 3mf C. mf/3 D. mf/9

Answer»

B. 3mf

Frequency multiplier increase the deviation,

β = Δf/fm

If multiplied by three,3 β = 3Δf/fm

Discussion

26554.	A DSB-SC signal is generated using the carrier cos(2πfc t + \(\theta\)) and modulating signal x(t). The envelop of the DSB-SC signal is (a) x(t) (b) \|(t)\| (c) Only positive portion of x(t) (d) (t) cos \(\theta\)
Answer» (b) \|(t)\| Given Carrier c(t) = cos(2πf_c t + θ) Modulating signal m(t) = x(t) DSB SC modulated signal is given by m(t).s(t) = cos(2πf_c t + θ)x(t) = x(t) { cos2πf_c t cos θ - sin2πf_c t sin θ} = x(t) cos2πf_c t cosθ – x(t) sin2πf_c t sin θ = x(t)

26554.

A DSB-SC signal is generated using the carrier cos(2πfc t + \(\theta\)) and modulating signal x(t). The envelop of the DSB-SC signal is (a) x(t) (b) |(t)| (c) Only positive portion of x(t) (d) (t) cos \(\theta\)

Answer»

(b) |(t)|

Given

Carrier c(t) = cos(2πf_c t + θ)

Modulating signal m(t) = x(t)

DSB SC modulated signal is given by m(t).s(t)

= cos(2πf_c t + θ)x(t)

= x(t) { cos2πf_c t cos θ - sin2πf_c t sin θ}

= x(t) cos2πf_c t cosθ – x(t) sin2πf_c t sin θ

= x(t)

Discussion

26555.	The base-emitter voltage of an ideal transistor is a. 0 b. 0.3 V c. 0.7 V d. 1 V
Answer» The correct answer is: (a) 0

Discussion

26556.	VSB modulation is preferred in TV becauseA. it reduces the bandwidth requirement to half B. it avoids phase distortion at low frequencies C. it results in better reception D. None of the above
Answer» D. None of the above VSB (vestigial side band) transmission transmits one side band fully and the other side band partially thus, reducing the bandwidth requirement.

26556.

VSB modulation is preferred in TV becauseA. it reduces the bandwidth requirement to half B. it avoids phase distortion at low frequencies C. it results in better reception D. None of the above

Answer»

D. None of the above

VSB (vestigial side band) transmission transmits one side band fully and the other side band partially thus, reducing the bandwidth requirement.

Discussion

26557.	If you recalculate the collector-emitter voltage with the second approximation, the answer will usually be a. Smaller than the ideal value b.. The same as the ideal value c. Larger than the ideal value d. Inaccurate
Answer» (c) Larger than the ideal value

Discussion

26558.	The base-emitter voltage of the second approximation is a. 0 b. 0.3 V c. 0.7 V d. 1 V
Answer» The correct answer is: (c) 0.7 V

Discussion

26559.	If the collector resistance increases in a VDB circuit, the collector voltage willa. Decrease b. Stay the same c. Increase d. Double
Answer» (a) Decrease

Discussion

26560.	The Q point of a VDB circuit is a. Hypersensitive to changes in current gain b. Somewhat sensitive to changes in current gain c. Almost totally insensitive to changes in current gain d. Greatly affected by temperature changes
Answer» (c) Almost totally insensitive to changes in current gain

Discussion

26561.	The first step in analyzing emitter-based circuits is to find the a. Base current b. Emitter voltage c. Emitter current d. Collector current
Answer» (b) Emitter voltage

Discussion

26562.	The base voltage of two-supply emitter bias (TSEB) is a. 0.7 V b. Very large c. Near 0 V d. 1.3 V
Answer» (c) Near 0 V

Discussion

26563.	A circuit with a fixed emitter current is called a. Base bias b. Emitter bias c. Transistor bias d. Two-supply bias
Answer» (b) Emitter bias

Discussion

26564.	The bulk resistance of a 1N4001 is a. 0 b. 0.23 ohm c. 10 ohm d. 1 kohm
Answer» The correct answer is: (b). 0.23 ohm

Discussion

26565.	How much forward diode voltage is there with the ideal-diode approximation? a. 0 b. 0.7 V c. More than 0.7 V d. 1 V
Answer» The correct answer is: (a) 0

Discussion

26566.	How much current is there through the second approximation of a silicon diode when it is reverse biased? a. 0 b. 1 mA c. 300 mA d. None of the above
Answer» The correct answer is: (a) 0

Discussion

26567.	How much voltage is there across the second approximation of a silicon diode when it is forward biased? a. 0 b. 0.3 V c. 0.7 V d. 1 V
Answer» The correct answer is: (c) 0.7 V

Discussion

26568.	The reverse current consists of minority-carrier current and a. Avalanche current b. Forward current c. Surface-leakage current d. Zener current
Answer» (c) Surface-leakage current

Discussion

26569.	With a full-wave rectified voltage across the load resistor, load current flows for what part of a cycle? a. 0 degrees b. 90 degrees c. 180 degrees d. 360 degrees
Answer» (d) 360 degrees

Discussion

26570.	What is the peak load voltage out of a bridge rectifier for a secondary voltage of 15 V rms? (Use second approximation.) a. 9.2 V b. 15 V c. 19.8 V d. 24.3 V
Answer» The correct answer is: (c) 19.8 V

Discussion

26571.	If line frequency is 60 Hz, the output frequency of a half-wave rectifier is a. 30 Hz b. 60 Hz c. 120 Hz d. 240 Hz
Answer» The correct answer is: (b) 60 Hz

Discussion

26572.	The voltage across the zener resistance is usually a. Small b. Large c. Measured in volts d. Subtracted from the breakdown voltage
Answer» The correct answer is: (a) Small

Discussion

26573.	The collector current is 10 mA. If the current gain is 100, the base current is a. 1 microamp b. 10 microamp c. 100 microamp d. 1 mA
Answer» (c) 100 microamp

Discussion

26574.	The base current is 50 microamp. If the current gain is 125, the collector current is closest in value to a. 40 microamp b. 500 microamp c. 1 mA d. 6 mA
Answer» The correct answer is: (d) 6 mA

Discussion

26575.	Most small-signal E-MOSFETs are found in a. Heavy-current applications b. Discrete circuits c. Disk drives d. Integrated circuits
Answer» (d) Integrated circuits

Discussion

26576.	If line frequency is 60 Hz, the output frequency of a bridge rectifier is a. 30 Hz b. 60 Hz c. 120 Hz d. 240 Hz
Answer» The correct answer is: (c) 120 Hz

Discussion

26577.	With the same secondary voltage and filter, which produces the least load voltage? a. Half-wave rectifier b. Full-wave rectifier c. Bridge rectifier d. Impossible to say
Answer» (b) Full-wave rectifier

Discussion

26578.	Components are soldered together in a. Discrete circuits b. Integrated circuits c. SSI d. Monolithic ICs
Answer» (a) Discrete circuits

Discussion

26579.	The power dissipated by a transistor approximately equals the collector current times a. Base-emitter voltage b. Collector-emitter voltage c. Base supply voltage d. 0.7 V
Answer» (b) Collector-emitter voltage

Discussion

26580.	With the same secondary voltage and filter, which has the most ripple? a. Half-wave rectifier b. Full-wave rectifier c. Bridge rectifier d. Impossible to say
Answer» (a) Half-wave rectifier

Discussion

26581.	If the filtered load current is 10 mA, which of the following has a diode current of 10 mA? a. Half-wave rectifier b. Full-wave rectifier c. Bridge rectifier d. Impossible to say
Answer» (a) Half-wave rectifier

Discussion

26582.	In a loaded zener regulator, which is the largest current? a. Series current b. Zener current c. Load current d. None of these
Answer» (a) Series current

Discussion

26583.	The diodes in a bridge rectifier each have a maximum dc current rating of 2 A. This means the dc load current can have a maximum value of a. 1 A b. 2 A c. 4 A d. 8 A
Answer» The correct answer is: (c) 4 A

Discussion

26584.	If the line voltage is 115 V rms, a turns ratio of 5: 1 means the rms secondary voltage is closest to a. 15 V b. 23 V c. 30 V d. 35 V
Answer» The correct answer is: (b) 23 V

Discussion

26585.	What is peak lead voltage in full wave rectifier if secondary voltage is 20 vrms
Answer» V_rms= 20 V_p = ? V_plak = V_rms√2 V_plak = 20 x √2 volt

26585.

What is peak lead voltage in full wave rectifier if secondary voltage is 20 vrms

Answer»

V_rms= 20

V_p = ?

V_plak = V_rms√2

V_plak = 20 x √2 volt

Discussion

26586.	What is the peak load voltage in a full-wave rectifier if the secondary voltage is 20 V rms? a. 0 V b. 0.7 V c. 14.1 V d. 28.3 V
Answer» The correct answer is: (d) 28.3 V

Discussion

26587.	The tail current of a diff amp is a. Half of either collector current b. Equal to either collector current c. Two times either collector current d. Equal to the difference in base currents
Answer» (c) Two times either collector current

Discussion

26588.	The input offset current equals the a. Difference between two base currents b. Average of two base currents c. Collector current divided by current gain d. Difference between two base-emitter voltages
Answer» (a) Difference between two base currents

Discussion

26589.	The collector-emitter voltage is usually a. Less than the collector supply voltage b. Equal to the collector supply voltage c. More than the collector supply voltage d. Cannot answer
Answer» (a) Less than the collector supply voltage

Discussion

26590.	When the reverse voltage increases, the capacitance a. Decreases b. Stays the same c. Increases d. Has more bandwidth
Answer» (a) Decreases

Discussion

26591.	The barrier potential across each silicon depletion layer is a. 0 b. 0.3 V c. 0.7 V d. 1 V
Answer» The correct answer is: (c) 0.7 V

Discussion

26592.	The emitter diode is usually a. Forward-biased b. Reverse-biased c. Nonconducting d. Operating in the breakdown region
Answer» (a) Forward-biased

Discussion

26593.	How is a nonconducting diode biased? a. Forward b. Inverse c. Poorly d. Reverse
Answer» The correct answer is: (d) Reverse

Discussion

26594.	A series regulator is an example of a a. Linear regulator b. Switching regulator c. Shunt regulator . Dc-to-dc converter
Answer» (a) Linear regulator

Discussion

26595.	An increase of line voltage into a power supply usually produces a. A decrease in load resistance b. An increase in load voltage c. A decrease in efficiency d. Less power dissipation in the rectifier diodes
Answer» (b) An increase in load voltage

Discussion

26596.	Why do we prefer a convex mirror as a rear-view mirror in vehicles?
Answer» Image formed by a concex mirror is always virtual, erect and smaller than the object. They are more helpful than the plane mirror because they can capture a wider range.

Discussion

26597.	A series regulator is more efficient than a shunt regulator because a. It has a series resistor b. It can boost the voltage c. The pass transistor replaces the series resistor d. It switches the pass transistor on and off
Answer» (c) The pass transistor replaces the series resistor

Discussion

26598.	A switching regulator is considered a. Quiet b. Noisy c. Inefficient d. Linear
Answer» The answer is: (b) Noisy

Discussion

26599.	In a boost regulator, the output voltage is filtered with a a. Choke-input filter b. Capacitor-input filter c. Diode d. Voltage divider
Answer» (b) Capacitor-input filter

Discussion

26600.	A current-sensing resistor is usually a. Zero b. Small c. Large d. Open
Answer» The answer is: (b) Small

Discussion

Explore topic-wise InterviewSolutions in .

In commercial TV transmission in India, picture and speech signals are modulated respectively(Picture)(Speech)(a)VSBVSB(b)VSBSSB(c)VSBFM(d)FMVSB

A 4 GHz carrier is DSB-SC modulated by a low-pass message signal with maximum frequency of 2 MHz. The resultant signal is to be ideally sampled. The minimum frequency of the sampling impulse train should be (a) 4 MHz (b) 8 MHz (c) 8 GHz (d) 8.004 GHz

In FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of A. mf B. 3mf C. mf/3 D. mf/9

A DSB-SC signal is generated using the carrier cos(2πfc t + \(\theta\)) and modulating signal x(t). The envelop of the DSB-SC signal is (a) x(t) (b) |(t)| (c) Only positive portion of x(t) (d) (t) cos \(\theta\)

The base-emitter voltage of an ideal transistor is a. 0 b. 0.3 V c. 0.7 V d. 1 V

VSB modulation is preferred in TV becauseA. it reduces the bandwidth requirement to half B. it avoids phase distortion at low frequencies C. it results in better reception D. None of the above

If you recalculate the collector-emitter voltage with the second approximation, the answer will usually be a. Smaller than the ideal value b.. The same as the ideal value c. Larger than the ideal value d. Inaccurate

The base-emitter voltage of the second approximation is a. 0 b. 0.3 V c. 0.7 V d. 1 V

If the collector resistance increases in a VDB circuit, the collector voltage willa. Decrease b. Stay the same c. Increase d. Double

The Q point of a VDB circuit is a. Hypersensitive to changes in current gain b. Somewhat sensitive to changes in current gain c. Almost totally insensitive to changes in current gain d. Greatly affected by temperature changes

The first step in analyzing emitter-based circuits is to find the a. Base current b. Emitter voltage c. Emitter current d. Collector current

The base voltage of two-supply emitter bias (TSEB) is a. 0.7 V b. Very large c. Near 0 V d. 1.3 V

A circuit with a fixed emitter current is called a. Base bias b. Emitter bias c. Transistor bias d. Two-supply bias

The bulk resistance of a 1N4001 is a. 0 b. 0.23 ohm c. 10 ohm d. 1 kohm

How much forward diode voltage is there with the ideal-diode approximation? a. 0 b. 0.7 V c. More than 0.7 V d. 1 V

How much current is there through the second approximation of a silicon diode when it is reverse biased? a. 0 b. 1 mA c. 300 mA d. None of the above

How much voltage is there across the second approximation of a silicon diode when it is forward biased? a. 0 b. 0.3 V c. 0.7 V d. 1 V

The reverse current consists of minority-carrier current and a. Avalanche current b. Forward current c. Surface-leakage current d. Zener current

With a full-wave rectified voltage across the load resistor, load current flows for what part of a cycle? a. 0 degrees b. 90 degrees c. 180 degrees d. 360 degrees

What is the peak load voltage out of a bridge rectifier for a secondary voltage of 15 V rms? (Use second approximation.) a. 9.2 V b. 15 V c. 19.8 V d. 24.3 V

If line frequency is 60 Hz, the output frequency of a half-wave rectifier is a. 30 Hz b. 60 Hz c. 120 Hz d. 240 Hz

The voltage across the zener resistance is usually a. Small b. Large c. Measured in volts d. Subtracted from the breakdown voltage

The collector current is 10 mA. If the current gain is 100, the base current is a. 1 microamp b. 10 microamp c. 100 microamp d. 1 mA

The base current is 50 microamp. If the current gain is 125, the collector current is closest in value to a. 40 microamp b. 500 microamp c. 1 mA d. 6 mA

Most small-signal E-MOSFETs are found in a. Heavy-current applications b. Discrete circuits c. Disk drives d. Integrated circuits

If line frequency is 60 Hz, the output frequency of a bridge rectifier is a. 30 Hz b. 60 Hz c. 120 Hz d. 240 Hz

With the same secondary voltage and filter, which produces the least load voltage? a. Half-wave rectifier b. Full-wave rectifier c. Bridge rectifier d. Impossible to say

Components are soldered together in a. Discrete circuits b. Integrated circuits c. SSI d. Monolithic ICs

The power dissipated by a transistor approximately equals the collector current times a. Base-emitter voltage b. Collector-emitter voltage c. Base supply voltage d. 0.7 V

With the same secondary voltage and filter, which has the most ripple? a. Half-wave rectifier b. Full-wave rectifier c. Bridge rectifier d. Impossible to say

If the filtered load current is 10 mA, which of the following has a diode current of 10 mA? a. Half-wave rectifier b. Full-wave rectifier c. Bridge rectifier d. Impossible to say

In a loaded zener regulator, which is the largest current? a. Series current b. Zener current c. Load current d. None of these

The diodes in a bridge rectifier each have a maximum dc current rating of 2 A. This means the dc load current can have a maximum value of a. 1 A b. 2 A c. 4 A d. 8 A

If the line voltage is 115 V rms, a turns ratio of 5: 1 means the rms secondary voltage is closest to a. 15 V b. 23 V c. 30 V d. 35 V

What is peak lead voltage in full wave rectifier if secondary voltage is 20 vrms

What is the peak load voltage in a full-wave rectifier if the secondary voltage is 20 V rms? a. 0 V b. 0.7 V c. 14.1 V d. 28.3 V

The tail current of a diff amp is a. Half of either collector current b. Equal to either collector current c. Two times either collector current d. Equal to the difference in base currents

The input offset current equals the a. Difference between two base currents b. Average of two base currents c. Collector current divided by current gain d. Difference between two base-emitter voltages

The collector-emitter voltage is usually a. Less than the collector supply voltage b. Equal to the collector supply voltage c. More than the collector supply voltage d. Cannot answer

When the reverse voltage increases, the capacitance a. Decreases b. Stays the same c. Increases d. Has more bandwidth

The barrier potential across each silicon depletion layer is a. 0 b. 0.3 V c. 0.7 V d. 1 V

The emitter diode is usually a. Forward-biased b. Reverse-biased c. Nonconducting d. Operating in the breakdown region

How is a nonconducting diode biased? a. Forward b. Inverse c. Poorly d. Reverse

A series regulator is an example of a a. Linear regulator b. Switching regulator c. Shunt regulator . Dc-to-dc converter

An increase of line voltage into a power supply usually produces a. A decrease in load resistance b. An increase in load voltage c. A decrease in efficiency d. Less power dissipation in the rectifier diodes

Why do we prefer a convex mirror as a rear-view mirror in vehicles?

A series regulator is more efficient than a shunt regulator because a. It has a series resistor b. It can boost the voltage c. The pass transistor replaces the series resistor d. It switches the pass transistor on and off

A switching regulator is considered a. Quiet b. Noisy c. Inefficient d. Linear

In a boost regulator, the output voltage is filtered with a a. Choke-input filter b. Capacitor-input filter c. Diode d. Voltage divider

A current-sensing resistor is usually a. Zero b. Small c. Large d. Open