An n - type semiconductor is formed

When germanium crystal is doped with an impurity containing three valence electron

When germanium crystal is doped with an impurity containing five valence electron

The absorption of radio waves by the atmosphere depends on

The polarisation of the atmosphere

Their distance from the transmitter

The polarisation of the atmosphere

Modem is a device used for

Converting anaglog signals to digital signals

The electrical conductivity of a pure silicon sample can be increased by

Doping it with acceptor and donor impurity

Shining ultraviolet light on it

In a transistor the emitter current is

Slightly less than the collector current

Slightly more than the collector current

Slightly less than the collector current

In an intrinsic semiconductor

Only electrons are responsible for the blow of current

Only holes are responsible for the blow of current

Both holes and electrons carry current and their number is the same

A pure semiconductor has

A finite resistance which increases with temperature

A finite resistance which does not depend upon temperature

A finite resistance which decreases with temperature

A finite resistance which increases with temperature

Metallic solids are always opaque because

The energy band traps the incident light

They reflect all the incident light

They scatter all the incident light

The incident light is readily absorbed by free electrons in a metal

The energy band traps the incident light

Resistive its resonant frequency

Resistive at resonant frequency

In black and white televisions, pictures on the screen are produced due to bombardment of

X - ray photons on a white screen

X - ray photons on a white fluorescent screen

Electrons on a fluorescent white screen

What does the term Dolby B or Dolby C printed on tape recorders and other sound systems refer to ?

Both DC and AC power can be used

In a p-type semiconductor,

Electrons are the only carriers

Holes are the majority carriers and electrons are the minority carriers

In the use of transistor as an amplifier

Both the junctions are forward biased

The emitter - base junction is forward biased and the collector - base junction is reverse biased

Both the junctions are forward biased

Any of the two junctions may be forward biased

95 + Mcqs in Electronic devices & Communication system in Physics Page 1 McqOptions

1.	The magnetic needle always points in _________ direction.
A.	East - West
B.	West - South
C.	North - South
D.	North - East
Answer» D. North - East

Discussion

2.	Who was the inventor of Radar ?
A.	Robert Watson
B.	Fleming
C.	Bush Wall
D.	Austin
Answer» B. Fleming

Discussion

3.	CT scan is done by using
A.	Infra-red rays
B.	Ultrasonic waves
C.	Visible lights
D.	X- rays
Answer» E.

Discussion

4.	Recently developed technique for monitoring fetal growth is
A.	Microwave technique
B.	Ultrasonic
C.	Ultra-violet rays
D.	X-rays
Answer» C. Ultra-violet rays

Discussion

5.	Light from the sun reaches earth in about
A.	2 minutes
B.	4 minutes
C.	8 minutes
D.	16 minutes
Answer» D. 16 minutes

Discussion

6.	Intelsat satellite works as a
A.	Transmitter
B.	Repeater
C.	Absorber
D.	None of these
Answer» C. Absorber

Discussion

7.	Which of the following device is full duplex ?
A.	Mobile phone
B.	Walky - talky
C.	Loudspeaker
D.	Radio
Answer» B. Walky - talky

Discussion

8.	An n - type semiconductor is formed
A.	When germanium crystal is doped with an impurity containing three valence electron
B.	When germanium crystal is doped with an impurity containing five valence electron
C.	From pure germanium
D.	From pure silicon
Answer» C. From pure germanium

Discussion

9.	Which of the following satellites is used in ship - to - shore and shore - to - shore and shore - to - ship communication ?
A.	Intelsat
B.	Marisat
C.	Comsat
D.	Telestar
Answer» C. Comsat

Discussion

10.	Intelsat satellite is user for
A.	Radio communication
B.	Intercontinental communication
C.	Radar communication
D.	None of the above
Answer» C. Radar communication

Discussion

11.	The electrical circuits used to get smooth do output from a rectified circuit is called
A.	Oscillator
B.	Full wave rectifier
C.	Amplifier
D.	Filter
Answer» E.

Discussion

12.	When the temperature of semiconductor is increased, its electrical conductivity
A.	Increases
B.	Remains the same
C.	Devreases
D.	None of these
Answer» B. Remains the same

Discussion

13.	With the rise of temperature, the specific resistance of semiconductor
A.	Increases
B.	Remains unchanged
C.	Decreases
D.	None of these
Answer» D. None of these

Discussion

14.	The technique of collecting information about an object from a distance without making physical contact with it is
A.	Remote sensing
B.	Remote control
C.	Remote accessing
D.	Space shuttle
Answer» B. Remote control

Discussion

15.	The frequency band used for radar relay - systems and television is
A.	UHF
B.	VLF
C.	VHF
D.	EHF
Answer» B. VLF

Discussion

16.	The absorption of radio waves by the atmosphere depends on
A.	Their distance from the transmitter
B.	Their polarisation of the wave
C.	Their frequency
D.	The polarisation of the atmosphere
Answer» D. The polarisation of the atmosphere

Discussion

17.	An oscillator is nothing but an amplifier with
A.	Positive feedback
B.	Large gain
C.	No feedback
D.	Negative feedback
Answer» B. Large gain

Discussion

18.	The space waves which are affected seriously by atmospheric conditions are
A.	MF0
B.	HF
C.	VHF
D.	UHF
Answer» E.

Discussion

19.	Which of the following is not transducer ?
A.	Loudspeaker
B.	Amplifier
C.	Microphone
D.	All of these
Answer» C. Microphone

Discussion

20.	Radio wave of constant amplitude can be generated with
A.	Filter
B.	Rectifier
C.	FET
D.	Oscillator
Answer» E.

Discussion

21.	The waves relevant to telecommunications are
A.	Visible light
B.	Infrared
C.	Ultraviolet
D.	Microwave
Answer» E.

Discussion

22.	Modem is a device used for
A.	Modulating signals
B.	Converting anaglog signals to digital signals
C.	Either of the above
D.	None of the above
Answer» C. Either of the above

Discussion

23.	A digital signal possesses
A.	Continuously varying values
B.	Only two discrete values
C.	Only four discrete values
D.	None of the above
Answer» C. Only four discrete values

Discussion

24.	The electrical conductivity of a pure silicon sample can be increased by
A.	Increasing the temperature
B.	Doping it with acceptor and donor impurity
C.	Shining ultraviolet light on it
D.	All of the above
Answer» E.

Discussion

25.	Which of the following is not a semiconductor ?
A.	Germinium
B.	Silicon
C.	Arsenic
D.	All of these
Answer» D. All of these

Discussion

26.	The electrical circuit used to get smooth DC output from a rectifier circuit is called
A.	Amplifer
B.	Filter
C.	Oscillator
D.	Full rectifier
Answer» C. Oscillator

Discussion

27.	In a transistor the emitter current is
A.	Slightly more than the collector current
B.	Slightly less than the collector current
C.	Equal to the collector current
D.	Equal to the base current
Answer» B. Slightly less than the collector current

Discussion

28.	In an intrinsic semiconductor
A.	Only electrons are responsible for the blow of current
B.	Only holes are responsible for the blow of current
C.	Both holes and electrons carry current and their number is the same
D.	None of the above
Answer» D. None of the above

Discussion

29.	If germanium has to be doped with a donor impurity, the foreign atom should be
A.	Tetravalent
B.	Pentavalent
C.	Trivalent
D.	None of these
Answer» C. Trivalent

Discussion

30.	A hole in p-type semiconductor is
A.	An excess electron
B.	A missing electron
C.	A missing atom
D.	A donor level
Answer» C. A missing atom

Discussion

31.	A pure semiconductor has
A.	An finite resistance at 0 C
B.	A finite resistance which does not depend upon temperature
C.	A finite resistance which decreases with temperature
D.	A finite resistance which increases with temperature
Answer» D. A finite resistance which increases with temperature

Discussion

32.	Long distance short - wave radio broad casting uses
A.	Ground wave
B.	Ionospheric wave
C.	Direct wave
D.	Sky wave
Answer» C. Direct wave

Discussion

33.	The positive charge carriers in semiconductor are
A.	Positive ions
B.	Protons
C.	Positrons
D.	Holes
Answer» E.

Discussion

34.	Metallic solids are always opaque because
A.	They reflect all the incident light
B.	They scatter all the incident light
C.	The incident light is readily absorbed by free electrons in a metal
D.	The energy band traps the incident light
Answer» D. The energy band traps the incident light

Discussion

35.	A typical Example of a semiconductor is
A.	Platinum
B.	Germanium
C.	Quartz
D.	Mica
Answer» C. Quartz

Discussion

36.	Antenna is
A.	Inductive
B.	Capacitive
C.	Resistive its resonant frequency
D.	Resistive at resonant frequency
Answer» B. Capacitive

Discussion

37.	Through which mode of propagation the radio waves can be sent from one place to another ?
A.	Ground wave propagation
B.	Sky wave propagation
C.	Space wave propagation
D.	All of the above
Answer» E.

Discussion

38.	The resistance of a pn junction in forward bias is
A.	Zero
B.	Low
C.	High
D.	Infinite
Answer» C. High

Discussion

39.	In black and white televisions, pictures on the screen are produced due to bombardment of
A.	X - ray photons on a white screen
B.	X - ray photons on a white fluorescent screen
C.	Electrons on a white screen
D.	Electrons on a fluorescent white screen
Answer» E.

Discussion

40.	What does the term Dolby B or Dolby C printed on tape recorders and other sound systems refer to ?
A.	Frequency modulated system
B.	Amplitude modulated system
C.	Nose reduction circuit
D.	Both DC and AC power can be used
Answer» D. Both DC and AC power can be used

Discussion

41.	In a p-type semiconductor,
A.	Holes are the only carriers
B.	Electrons are the only carriers
C.	Holes are the majority carriers and electrons are the minority carriers
D.	None of the above
Answer» D. None of the above

Discussion

42.	The unidirectional property of a pn-junction is useful for its use as a
A.	Rectifier
B.	Oscillator
C.	Rectifier
D.	Transformer
Answer» B. Oscillator

Discussion

43.	When arsenic is added as an impurity to silicon, the resulting material is
A.	n-type semiconductor
B.	p-type semiconductor
C.	n-type conductor
D.	None of these
Answer» B. p-type semiconductor

Discussion

44.	In the use of transistor as an amplifier
A.	The emitter - base junction is forward biased and the collector - base junction is reverse biased
B.	Both the junctions are forward biased
C.	Any of the two junctions may be forward biased
D.	None of the above
Answer» B. Both the junctions are forward biased

Discussion

45.	The impurity atoms with which pure silicon should be doped to make a p-type semiconductor are those of
A.	Phosphorus
B.	Boron
C.	Aluminium
D.	Both (b) and (c)
Answer» E.

Discussion

46.	In a p-type semiconductor the majority charge carriers are
A.	Electrons
B.	Holes
C.	Neutrons
D.	Protons
Answer» C. Neutrons

Discussion

47.	Consider the following statements 1. In a semiconductor, the uppermost band is the valence band 2. All semiconductors are electrically neutral 3. With increase of temperature the resistivity of semiconductor decreases 4. Addition of a small amount of impurity of a III or V group elements to a pure semiconductor increases its resistivity Choose the correct statements
A.	1 and 2
B.	2 and 3
C.	3 and 4
D.	1 and 4
Answer» C. 3 and 4

Discussion

48.	At zero degree kelvin a piece of germanium
A.	Becomes semiconductor
B.	Becomes good conductor
C.	Becomes bad conductor
D.	None of the above
Answer» D. None of the above

Discussion

49.	n-type of semiconductor is
A.	Negatively charged
B.	Positively charged
C.	Neutral
D.	None of these
Answer» D. None of these

Discussion

50.

Match the quantities of Column I with the corresponding quantities in Column II
Column - I Column - II
F Germanium at 0K 1. Intrinsic semiconductor
G Germanium at room temperature 2. Insulator
H Germanium doped with indium 3. n-type semiconductor
J Germanium doped 4. p-type semiconductor
Codes :
F G H J
A. 1 2 3 4
B. 2 1 4 3
C. 2 1 3 4
D. 1 2 4 3

A.

B.

C.

D.

Answer» C. C.

Discussion

Explore topic-wise MCQs in Physics.

The magnetic needle always points in _________ direction.

Who was the inventor of Radar ?

CT scan is done by using

Recently developed technique for monitoring fetal growth is

Light from the sun reaches earth in about

Intelsat satellite works as a

Which of the following device is full duplex ?

An n - type semiconductor is formed

Which of the following satellites is used in ship - to - shore and shore - to - shore and shore - to - ship communication ?

Intelsat satellite is user for

The electrical circuits used to get smooth do output from a rectified circuit is called

When the temperature of semiconductor is increased, its electrical conductivity

With the rise of temperature, the specific resistance of semiconductor

The technique of collecting information about an object from a distance without making physical contact with it is

The frequency band used for radar relay - systems and television is

The absorption of radio waves by the atmosphere depends on

An oscillator is nothing but an amplifier with

The space waves which are affected seriously by atmospheric conditions are

Which of the following is not transducer ?

Radio wave of constant amplitude can be generated with

The waves relevant to telecommunications are

Modem is a device used for

A digital signal possesses

The electrical conductivity of a pure silicon sample can be increased by

Which of the following is not a semiconductor ?

The electrical circuit used to get smooth DC output from a rectifier circuit is called

In a transistor the emitter current is

In an intrinsic semiconductor

If germanium has to be doped with a donor impurity, the foreign atom should be

A hole in p-type semiconductor is

A pure semiconductor has

Long distance short - wave radio broad casting uses

The positive charge carriers in semiconductor are

Metallic solids are always opaque because

A typical Example of a semiconductor is

Antenna is

Through which mode of propagation the radio waves can be sent from one place to another ?

The resistance of a pn junction in forward bias is

In black and white televisions, pictures on the screen are produced due to bombardment of

What does the term Dolby B or Dolby C printed on tape recorders and other sound systems refer to ?

In a p-type semiconductor,

The unidirectional property of a pn-junction is useful for its use as a

When arsenic is added as an impurity to silicon, the resulting material is

In the use of transistor as an amplifier

The impurity atoms with which pure silicon should be doped to make a p-type semiconductor are those of

In a p-type semiconductor the majority charge carriers are

At zero degree kelvin a piece of germanium

n-type of semiconductor is